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PRINCIPLES 



OF 



ECONOMIC ZOOLOGY 



BY 

L. S. DAUGHERTY, M.S., Ph.D. 

PROFESSOR OF ZOOLOGY, STATE NORMAL SCHOOL, KIRKSVJLLE, MO. 

AND 

M. C. DAUGHERTY 

AUTHOR WITH JACKSON OF "AGRICULTURE THROUGH THE LABORATORV 
AND SCHOOL GARDEN " 



SECOND EDITION, REVISED 
WITH 301 ILLUSTRATIONS 



PHILADELPHIA AND LONDON 

W. B. SAUNDERS COMPANY 

1917 



■33z 



Copyright, igi2, by W. B. Saunders Company. Reprinted May, 1915. 
Revised, reprinted, and recopyrighted September, 1917 



Copyright, 1917, by W. B. Saunders Company 



AUG 181917 



PRINTED IN AMERICA 



PRESS OF 

W. B. SAUNDERS COMPANV 

PHILADELPHIA 



©CI.A473152 



PREFACE TO THE SECOND EDITION 



The authors have corrected some errors that crept into 
the first edition. We have added suggestions, problems, and 
questions which we hope will be of use to our fellow teachers. 

We have diligently compared our text with the latest Ger- 
man, French, English, and American Zoologies, and we be- 
lieve we have given the correct facts. 

The Authors. 

September, 1917. 



PREFACE 



The authors have long felt the need of one book in the 
hands of the student which would give. not only the salient 
facts of structural Zoology and the development of the various 
branches of animals, but also such facts of natural history— or 
the life and habits of animals— as to show the interrelations of 
structure, habit, and environment. For we believe that a 
knowledge of both structure and life-history is necessary before 
any suggestions or discoveries can be made concerning the prin- 
ciples which underlie and control all animal life, including that 
of man. For it is principles and their application for which we 
are searching. 

This book is an attempt to supply this need. It is especi- 
ally designed to accompany the " Field and Laboratory Guide" 

(Part I). 

For the sake of the natural history many examples have 
been included. To reduce the size of the book it has been 
necessary to print this natural history in smaller type, but 
that in no way implies that it is of minor importance, and it is 
by far the most interesting portion of the subject. The scien- 
tific names need not, in all cases, be learned. They have been 
used because common names are so often misleading. 



VI PREFACE 

Much of the subject matter has been derived from our own 
observation and experience, but we have made use of material 
from all available sources and we have tried to give credit by 
continual reference to the authorities used. That a book of 
this character can never be original,' everyone knows. The 
scope is too great for the observations of one lifetime. 

We are aware that we have fallen far short of our ideal. 
But we believe the book will be of much service if followed as 
suggested and used in connection with Part I. "If a better 
system is thine, impart it frankly. If not, make use of mine." 

The Authors. 

KiRKSVILLE, Mo. 



CONTENTS 



PAGE 

Branch Protozoa 1 

Class I. Rhizopoda, 1. — Class II. Mastigophora, 4. — Class III. 
Sporozoa, 4. — Class IV. Infusoria, 5. 

Branch Porifera 10 

Branch Ccelenterata 17 

Class I. Hydrozoa, 18. — Class II. The Scyphozoa, 26. — Class 
III. Actinozoa, 26. — Class IV. Ctenophora, 31. 

Branch Platyhelminthes 34 

Class I. Turbellaria, 34. — Class II. Trematoda, 35. — Class III. 
Cestoda, 37. — Class IV. Nemertinea, 39. 

Branch Nemathelminthes 41 

Class I. Nematoda, 41. — Class II. Acanthocephala, 44. — Class 
III. Chsetognatha, 44. 

Branch Trochelminthes 46 

Class I. Rotifera, 46. — Class II. Dinophilea, 47. — Class III. 
Gastrotricha, 47. 

Branch Molluscoida 48 

Class I. Polyzoa, 48. — Class II. Phoronida, 48. — Class III. 
Brachiopoda, 48. 

Branch Echinodermata 50 

Class I. Asteroidea, 54. — Class II. Ophiuroidea, 56. — Class III. 
Echinoidea, 58. — Class IV. Holothuroidea, 60. — Class V. 
Crinoidea, 62. 

Branch Annulata 65 

Class I. Chsetopoda, 65. — Class II. Gephyrea, 69. — Class III. 
Hirudinea, 69. 

Branch Mollusca 72 

Class I. Pelecypoda, 73. — Class II. Gasteropoda, 81. — Class III. 
Cephalopoda, 84. 

vii 



VUl CONTENTS 

PAGE 

Branch Arthropoda 89 

Class I. Crustacea, 90. — Sub-olass Entomostraca, 90. — Order 

I. Phyllopoda, 90.— Order II. Ostracoda, 90.— Order III. Cope- 
poda, 91. — Order IV. Cirripedia or Barnacles, 91. — Sub-class 

II. Malacostraca, 92. — Order I. Phyllocardia, 93. — Order II. 
Decapoda, 93. — Order III. Arthrostraca, 102. 

Class II. Arachnida, 103. — Order I. Scorpionida, 103. — Order 
II. Phalansidea, 104. — Order III. Araneida or Spiders, 104. — 
Order IV. Xiphosura, 110. 

Class III. Myriapoda, 111. — Order I. Chilopoda, 111. — Order 
II. Diplopoda, 112. 

Class IV. Insects, 112. — Order I. Aptera or Thysanura, 126. — 
Order II. Ephemerida, 127.— Order III. Plecoptera, 128.— 
Order IV. Odonata, 129.— Order V. Isoptera, 131.— Order VI. 
Orthoptera, 132.— Order VII. Hemiptera, 140.— Order VIII. 
Coleoptera, 148. — Order IX. Diptera, 153. — Order X. Siphon- 
aptera, 161. — Order XI. Lepidoptera, 162. — Order XII. Hymen- 
optera, 174. 

Branch Chord ata 188 

Sub-phylum and Class I. Adelochorda, 191. — Sub-phylum and 
Class ll. Urochorda or Tunicata, 192. — Sub-phylum and 
Class III. Acrania or Amphioxus, 194. 

Sub-phylum, IV. Craniata or Vertebrata, 195. — Class I. Cy- 
clostomata, 195. 

Class II. Pisces, 196. — Sub-class I. Elasmobranchii, 206. — 
Sub-class II. Holocephali, 207.— Sub-class III. Dipnoi, 208.— 
Sub-class IV. Teleostomi, 209. — Order I. Crossopterygii, 210. — 
Order II. Chondrostei, 210.— Order III. Holostei, 210.— Order 
IV. Teleostei, 211. 

Class III. Amphibia, 221.— Order I. Stegocephala, 228.— Order 
II. Apoda or Gymnophiona, 228. — Orddr III. Urodela or Cau- 
data, 229.— Order IV. Anura or Ecaudata, 233. 

Class IV. Reptilia, 236.— Order I. Rhynchocephalia, 238.— 
Order II. Ophidia, 239.— Order III. Lacertilia, 243.— Order IV. 
Chelonia, 248.— Order V. Crocodilia, 253. 

Class V. Aves, 258. — Division A. Ratitoe, 278. — Division B. 
Carinatoe, 2Sl.— Water Birds: Order I. Pygopodes, 281.— Order 
II. Longipennes, 282.— Order III. Tubinares, 283.— Order IV. 
Steganopodes, 284.— Order V. Anseres, 285.— Order VI. Odon- 
toglossffi, 286.— Order VII. Herodiones, 286.- Order VIII. 
Paludicote, 289.- Order IX. Limicola?, 290.— Land Birds: 
Order X. Gallina', 291.— Order XI. Columba;, 292.— Order 
XII. Raptores, 294.— Order XIII. Psittaci, 297.— Order XIV. 
Coccyges, 297.— Order XV. Pici, 298.— Order XVI. Machro- 
chires, 300.— Order XVII. Passeres, 300. 



CONTENTS IX 

PAGE 



Class VI. Mammalia, 311. — Order I. Monotremata, 319. — 
Order II. Marsupialia, 320.— Order III. Edentata, 323. — Order 
IV. Sirenia, 325.— Order V. Cetacea, 326.— Order VI. Ungulata, 
329.— Order VII. Rodentia or Glires, 350.— Order VIII. Car- 
nivora, 356. — Order IX. Insectivora, 366. — Order X. Chirop- 
tera, 368.— Order XI. Primates, 372. 



Theories of Development 382 

Questions, Problems, and Suggestions 394 

Glossary 413 

Index 417 



"There are more things in heaven and earth, Horatio, 
Than are dreamt of in your philosophy." 

Shakespeare. 



PRINCIPLES OF 

ECONOMIC ZOOLOGY 



BRANCH PROTOZOA 

The- animals of this branch are one celled and microscopic, 
or very small. These cells may unite, but as the union is not 
organic, it is said to form a colony, and not an individual animal 
as is the case in the higher forms. A colony may consist of a 
few cells, as in Gonium, or of many cells, as in Volvox. 

Since protozoans are so minute and their soft protoplasmic 
substance is so easily dried up, they are usually aquatic, but 
some forms are parasitic, while others, as Amce'ha terric'ola, are 
terrestrial, but these hve or remain active in moist places only. 
Protozoans are most abundant in salt water, or in stagnant pools 
of fresh water, and are found in almost all parts of the globe. 

Since, by reason of their simplicity, protozoans are adapted 
for living where other animals could not exist, they are supposed 
to be the oldest or first animal life, and it is believed that they 
existed in the Archaean time. (See Fig. 302.) 

Numbers.— There are many thousands of species of these 
protozoans, each species differing from all others in some 
detail, yet all agreeing in their unicellular simplicity. Only a 
few of the typical forms can be mentioned. 

CLASS I. RHIZOPODA 

The lowest class, or RMzop'oda, is represented by the Amoeba 
(Fig. 1). It is an irregular mass of colorless, semifluid, or jelly- 
like living protoplasm destitute of a cell wall. There is no dis- 

1 



L BRANCH PROTOZOA 

tinct line between the clear outer homogeneous layer, or edo- 
plasfn, and the inner granular substance, the endoplasm. Within 
the endoplasm is the nucleus, a small, round, denser mass. 

Sometimes the contractile vacuole, a clear sphere of liquid and 
gas, appears, increases in size, then contracts, and disappears, 
and a new one is formed. This is supposed to aid in respiration 




Fig. 1. — Amoeba polypodia in six successive stages of division. The dark 
white-edged spot in the interior is the nucleus. (Schulze.) 



and in carrying off the waste products formed by oxidation, 
such as carbon dioxid. 

Motion and Locomotion. — Under the microscope the amoeba 
may be identified by its movements. The body surface will be 
seen to protrude or rather flow out at one or several points, 
forming irregular lobes, called false feet, or pseudopodia, which 



RHIZOPODA 6 

may be contracted, or the whole body protoplasm may flow- 
along after them, thus producing locomotion as well as constant 
change of form. 

According to the experiments of Professor H. S. Jennings, 
particles attached to the ectoplasm move forward on the upper 
surface, disappear over the anterior edge, and, as the proto- 
plasm flows along, appear again at the posterior end, to repeat 
the circuit, showing that this locomotion is a sort of " rolling 
process." 

Feeding. — As the amceba flows or rolls along, if it comes in 
contact with a particle which is unfit for food, it passes by or 
over it, but if the particle is fit for food, it flows about and en- 
velops it, and forms the so-called food vacuole. As this food 
vacuole moves along the endoplasm, the digestible part of the 
food disappears in digestion, while the indigestible portion is 
left behind as the protoplasmic body moves along. 

Multiplication in the case of the Amoeba is by binary division 
or fission and by sporulation. This becomes necessary, since 
the entire animal is but a single cell, and all the functions for 
the whole animal must be performed by this one cell. Hence, 
it must remain exceedingly small, so the nucleus, as well as the 
body substance, divides into two halves, and two individuals 
result. 

Encysting. — Under unfavorable environment, such as drouth, 
the Amoeba contracts into a tiny sphere, becomes encysted or 
encased in a horn-like membrane, and remains in a dormant 
condition until favorable environment returns to it, or it is trans- 
ported by the wind or carried by other animals— in the dirt 
which has clung to them — to a favorable environment, where 
it bursts its cyst and resumes active life. 

The Radiola'ria are marine Rhizopoda which have their pseudopodia 
arranged hke rays. Many of these forms possess a silicious shell or skele- 
ton, and myriads of these shells are found in rocks of various geologic 
ages. One type reproduces by swarm spores, the original nucleus dividing 
into hundreds of daughter-nuclei. 

The Foraminif era are Rhizopoda whose fresh-water forms have chitinous 
or silicious coverings, while the typical members, which are marine, have 
calcareous shells. When the animal dies the shell sinks to the bottom of 
the ocean. Such multitudes have existed that vast formations of chalk 
or limestone rock have been made by their shells. The stone of the Pyra- 
mids is said to be composed of fossil Foraminifera. 



4 BRANCH PROTOZOA 

It is said that in the bodies of some Radiolaria are found unicellular 
Algse, or microscopic plants, which furnish, even in this low stage of life, 
an example of symbiosis, or the living together of different kinds of organisms 
for mutual benefit. 

CLASS n, MASTIGOPHORA 

The Eugle'na is a representative of the second class of Pro- 
tozoans {Mastigoph'ora). It has a more fixed arrangement 
of parts than the Amoeba. The ceH is surrounded by a dehcate 
membrane perforated at the blunt anterior end by a funnel- 
shaped mouth through which the food passes into the body sub- 
stance. From the base of this mouth the protoplasm extends 
out in a long flagellum which, by its lashing, propels the body 
forward, and produces currents of water which bear food into 
the mouth. Back of the mouth is a tiny pigment spot beside a 
clear space which is sensitive to light. 



CLASS III. SPOROZOA 

This class consists of parasitic protozoans. The Gregari'na 
is parasitic in the intestines, reproductive organs, or, rarely, in 
the body cavity of invertebrates, such as crayfish, insects, and 
worms. It absorbs hquid food from its host and has no mouth 
nor pseudopodia. One or two individuals become encysted and 
then break up into a number of minute portions called spores. 

The Haemosporid'ia are sporozoans which live in the blood-corpuscles of 
vertebrates. In man they are the germs which produce malaria. The 
malaria-producing protozoans spend part of their life in man and part in a 
certain genus of mosquito Anoph'eles). When this mosquito sucks the 
blood of a malarial patient the germs are taken into the stomach of the 
mosquito. " After fertilization the oosphere wanders into the intestinal 
wall of the mosquito, grows larger, encysts, and produces many sporo- 
blasts, which in time form many sporozoites." These pass out with the 
saliva of the female Ano-ph'eles as it " bites " another person, and thus the 
germs of malaria are transferred to his blood, where, under proper condi- 
tions, they multiply rapidly, and fever results. It is evident thatthe bite 
of this mosquito does not cause malaria unless the mosquito is itself in- 
fected with the germs. 

Yellow fever is believed to be caused by another sporozoan carried by a 
different genus of mosquito {Stegomy'ia). (See p. 157.) 



INFUSORIA 



CLASS IV. INFUSORIA 

The fourth class of protozoans is the Infuso'ria, of which 
the Faramce-cium, or ''slipper animalcule," is a type (Fig. 2). 
It is somewhat cylindric in form and is surrounded by a cuticle 
perforated with minute openings, through 
which the protoplasm projects in the form 
of short hair-like structures, called cilia, 
which are the organs of locomotion. 
On the ventral surface of the Paramoecium 
is a groove which runs backward and 
inward into a short tube or gullet. Both 
the tube and the gullet are lined with 
vibrating cilia which cause currents of 
water. These currents carry the food into 
the inner end of the gullet, where it is 
pushed by occasional constrictions into the 
soft endoplasm and carried about in its 
movements as a food vacuole. The un- 
digested particles are cast out at a fixed 
point in the cell wall, but it is not per- 
manently open, so it is not easily recog- 
nized. The Paramoecium is supplied with 
two coiled threads which may be used 
as organs of defense. The Paramoecium 
has two nuclei, one, the macronucleus, 
supposed to be the seat of all vital func- 
tions, and the other, the micronucleus, 
which controls the reproduction. The 
Paramoecium reproduces by fission, both 
nuclei being divided, but conjugation 
also is manifested. In conjugation, 
two Paramoecia unite temporarily, ex- 
change a portion of the micronuclei, 
and perform other processes; they then 
separate, and continue more actively 
the process of transverse division or 
fission. 

While these examples are only a few of the thousands of 
species and of the countless myriads of individuals of proto- 
zoans, yet, if carefully studied, they teach many things. 




Fig. 2. — Paramoe- 
cium caudatum, from 
the ventral side, show- 
ing the vestibule en 
face; arrows inside the 
body indicate the di- 
rection of protoplasmic 
currents; those outside, 
the direction of water 
currents caused by the 
cilia, c.v, Contractile 
vacuoles; /.y, food vac- 
uoles; w.v, water vacu- 
oles; 7)1, mouth; mac, 
macronucleus; mic, mi- 
cronucleus; cp, esopha- 
gus; V, vestibule. The 
anterior end is directed 
upward. (Sedgwick 
and Wilson.) 



BRANCH PROTOZOA 




Fig. 3. — Organisms very abundantly found in common sea-water that 
has stood a few days in an open shallow dish: a, Acineta with embryo 
budding off; h, resting spores of alga, with bacteria; c, Chilodon; d, small 
Navicula; c, Cocconeis; /, larger species of Navicula; g, hehozoan, with 
two entrapped infusoria; h, germinating alga cells; i, small colony of bac- 
teria in zooglea stage with small flagellate infusoria near by; k, flagellate 
infusorian; /«, infusorian Mesodinium; n, ciliate infusorian; v, Vorticella, 
with small portion of its stalk. (Bull. U. S. F. C, 1895.) 



INFUSORIA 7 

Protoplasm. — Living protoplasm is the active substance of all 
living organisms. All the forces or conditions which tend to 
cause response or reaction in living protoplasm are called 
stimuli. The principal stimuli^ may be classed as chemical 
stimuh, differences in temperature, light, contact, electricity, 
and gravity. Protozoans possess: (1) Irritability, that property 
of living protoplasm which gives it power to respond to stimuli; 
(2) automatism, the power of movement, or of changing the form. 

Locomotion. — Protozoans move by means of pseudopodia, 
cilia, or fiagella. Some forms, as the Vorticel'la, are fixed, and 
can move only by the contractility of their stalks or stems. 

Nutrition. — The food of protozoans is composed of whatever 
minute organisms or fragments of organic matter they are 
able to obtain in the water. The parasitic forms, of course, 
simply absorb nutriment from the liquids of the host. The proc- 
ess of nutrition in the simplest protozoan consists in wrapping 
or, more correctly, flowing itself about the particle of food, 
absorbing the nutriment needed, and rejecting what it cannot 
use. Thus we see that it has the power of selective absorption, 
or digestion. 

Circulation is brought about by simply changing the form of 
the body mass, thus changing the position of the absorbed 
nutriment in the one-celled body. 

Assimilation, or the making of this absorbed material into 
its own body substance, next takes place, and, as a consequence, 
growth. The using up of assimilated material for heat or 
motion (energy), or metabolism, also takes place. 

1 The reactions (orientation) of animals in response to these various 
stimuh are called tropisms; the response to chemical stimuli is called 
chemotropism; to heat, thermotropism; to light, phototropism ; to contact, 
thigmotropisjn; to electricity, electrotropism; to gravity, geotropism, and sb 
on. Loeb and others claim that the movements of the lower forms and 
many of those of the higher forms are purely physical and chemical reac- 
tions, just exactly as those known to us in the inorganic world. H. S. 
Jennings, who is another very careful investigator, asserts that his inves- 
tigations show " that in these creatures their behavior is not, as a rule, on 
the tropism plan — a set, forced method of reacting to each particular agent 
— but takes place in a much more flexible, less directly, machine-like way 
by the method of trial and error. . . . This method leads upward, offer- 
ing at every point opportunity for development, and showing even in the 
unicellular organisms what must be considered the beginnings of intelli- 
gence and of many other qualities found in higher animals." 



8 .BRANCH PROTOZOA 

Respiration, or the taking in of oxygen and the giving off 
of carbonic acid gas and other wastes, is effected by the absorb- 
tion of the one and the throwing off of the other through the 
surface. 

Excretion takes place through the surface or through the 
contractile vacuole, there being a definite point at which the 
waste is ejected in the more advanced forms, such as the 
Paramcecium and the Vorticella. 

Multiplication, — While these life processes are going on, the 
animal grows or increases in size. This size must necessarily 
be very limited, for only small animals could live in this primi- 
tive way; hence, when the protozoan has reached a sufficient 
size, it divides into two complete halves, each half containing 
its share of the original cell-nucleus, as well as of the cytoplasm 
or protoplasmic cell body. This cell division, or the multiplica- 
tion of individuals, is called fission. After simple fission has 
taken place for many generations the fusion of two individuals, 
or conjugation, in which the nucleus of one individual is broken 
up and fused with that of the other, occurs. After this fusion, 
the process of fission continues, in which each new individual now 
contains a portion of the two parent nuclei which were fused 
in conjugation, instead of one parent nucleus as before con- 
jugation. This surely contains a suggestion of sexual mul- 
tiplication, though the conjugating cells may appear exactly 
alike. However, instances are given in which the individuals 
differ in size, the " males " being smaller and more mobile. 
Also we see, not exactly " alternation of generations," but, at 
any rate, alternation of methods of reproduction. 

Animal Mind.^ — Of the mental life of the protozoan little is 
known. If the rudiments of future complex animals is fore- 
shadowed in the protozoan, why may we not recognize the fact 
that here, too, is found the merest suggestion of the mental life 
as well? 

It has been abundantly demonstrated that protozoans possess 
irritability and contractility. It has been shown that they are 
sensitive to touch or contact, and, indeed, can discriminate 

1 Mind is here used in the biologic sense, and is the "sum total of all 
psychic changes, actions, and reactions." — Jordan and Kellogg's " Evolu- 
tion and Animal Life," p. 448. 



INFUSORIA 9 

between a hard substance and a softer substance suitable for 
food, as well as to recognize their kind by contact. 

Weir, in his '' Dawn of Reason," tells of observations with an 
Actino-pWrys, in which it was seen to discriminate between starch 
grains and uric-acid crystals. 

Protozoans are also known to be responsive to heat and light. 
Weir also states as his opinion that all animals can distinguish 
day from night. The question remains as to whether or not 
this is ascertained by sight. However this may be, there can 
be absolutely no vision, because there is no mechanism for it. 

Importance of Protozoans. — (1) They furnish, either directly 
or indirectly, food for all higher forms of life. (2) They are 
scavengers of decayed organic matter. (3) By their countless 
numbers throughout the ages, vast formations of chalk or lime- 
stone have been made. Myriads of them are still sinking to the 
bottom of the ocean as Gldb'igeri'na ooze or Radiolarian ooze. 
Since these animals are aquatic, geologists know that wherever 
these vast formations are found, there was once the sea. (4) 
Some of them are parasitic in the lower animals and in man, 
causing diseases which are ofttimes widespread and serious.^ 

Classification. — (Adapted from Parker and Haswell): 

Class. Examples. 

I. Rhizop'oda. Amoe'ba, etc. 

II. Mastigoph'ora. Eugle'na, Vol'vox. 

III. Sporozo'a. Gregarl'na, etc. 

IV. Infuso'ria. Paramce'cium and Vorticel'la. 

1 Colonial Protozoa. See Jordan's "Evolution and Animal Life," p. 217. 



BRANCH PORIFERA 

All animals except the Protozoans are multicellular and are 
classed as Metazoa. 

Differentiation. — In all we find, to a greater or less degree, 
division of labor among the cells, or the differentiation into tissues 
and organs for special functions. 

Reproduction. — True sexual reproduction is the characteristic 
method among Metazoans. 

Porifera. — These aquatic, many-celled animals were formerly 
considered as plants. Indeed, they look like seaweeds among 
the rocks at the bottom of the sea. Most of the sponges are 
marine, but there are a number of fresh-water forms. 

Fresh-water sponges are widely distributed, and are attached 
to weeds 'or submerged objects along the margins of clear 
springs or ponds. 

Sponges vary in color from a greenish hue to red, brown, or 
flesh color. All of the soft parts, as well as the skin or covering, 
is gone from the commercial sponges. 

Their shape, as is seen in the sponges of commerce, is irregu- 
lar even in the same species ; it varies with the environment, in 
order that the sponges may adapt themselves to the surface 
to which they are attached or the depth and currents of the 
water. Their size varies from a fraction of an inch to two or 
three feet in diameter. 

Structure. — The body of the Porifera consists of many cells 
arranged in two layers, an inner, or endoderm, and an outer, or 
ectoderm. There is a middle undifferentiated layer {mesoglea). 
The simplest sponge is cylindric or vase shaped (Fig. 4), 
while others, more complicated, consist of a system of branch- 
ing tubes. At the free end of each is a small opening, the 
osculum, or exhalant orifice, while the walls of the cylinder are 
perforated by exceedingly minute inhalant pores. The ecto- 
derm consists of flattened cells, which are also found to extend 
for a short distance inside the osculum, while the rest of the tube 

10 



MULTIPLICATION 



11 



is lined with a single layer of peculiarly shaped columnar cells, 
each possessing a flagellum. 

The skeleton is developed in the middle layer and may 
consist of silicious or of calcareous spicules of a great variety of 
form, sometimes they are anchor shaped,, 
and again others are club shaped, spear 
shaped, or cruciform. The so-called glass 
sponges sometimes have beautiful silici- 
ous skeletons. In other cases the skele- 
ton consists simply of fine, flexible, inter- 
woven fibers of tough, horny spongin. 
It is the skeleton, denuded of the flesh, 
or sarcode, that covers it in life, which 
forms the commercial sponge. A few 
sponges have no skeletons. 

Nutrition. — There are no organs of 
digestion, circulation, or respiration in 
the sponge. The food consists of micro- 
scopic plants or animals, or of minute 
particles of organic matter floating in 
the water. The food-laden water enters 
through the inhalant pores and is carried 
by the movement of the fiagella through 
the canals or paragastric cavities. The 
food as well as oxygen is taken up by 
the cells lining the canals and by the 
ameboid cells. The waste is carried out 
by the outgoing currents of water, which 
empty through the osculum, or, if the 
sponge is complex, the oscula. 

Locomotion. — At first the larval sponge 
is free swimming, by means of cilia. 
It soon becomes fixed to some stone 

or other object or animal, and assumes the fixed ways of its 
ancestors. 

Multiplication. — (1) Asexual, by external budding and the 
consequent formation of a united colony, or by internal gem- 
mules; (2) sexual, thus insuring the perpetuation of the species. 
Sponges are hermaphroditic, that is, both the male elements 




Fig. 4. — A simple 
sponge (Calcolynthus 
primigenius) with part 
of outer wall cut away. 
(After Hackel.) 



12 



BRANCH PORIFERA 



(sperm cells) and the female elements or eggs (ova) are con- 
tained in the same individual (Fig. 5). It is from the union 
of a sperm cell with an ovum that the new individual sponge 
is developed. The sperm cells and the ova rarely mature at 
the same time in the same individual. Hence, the ova in the 
canals of one sponge are fertilized by the spermatozoa of an- 
other sponge, which are carried to them by the afferent currents 
of water in the canals, thus insuring cross-fertilization. The 
eggs are retained in the canals until the blastula stage of their 




Fig. 5. — First stages in embryonic development of the pond snail 
(Lymnceus): a, Egg cell; b, first cleavage; c, second cleavage; d, third cleav- 
age; e, after numerous cleavages (Morula); /, blastula (in section); g, 
gastrula just forming (in section); h, gastrula completed (in section). 
(After Rabl.) This may be taken as a type of the earliest development of 
all many celled animals (Metazoa). (From Jordan and Kellogg, " Animal 
Life," D. Appleton and Co., Publishers.) 

development is reached, then they are set free and pass 
out at the exhalant opening or osculum. The fresh-water 
sponges (spongilla) bear small, seed-like bodies called gemmules 
toward the approach of winter. The parent sponge dies, the 
gemmules remain dormant until the next spring, when the rising 
temperature calls them to renewed life. They grow into 
mature spongilla, bear other gemmules, and thus the life- 
history of their race is repeated. 

Animal Mind. — Sponges have no well-marked nerve-cells, 
though the simplest elements of both nerve and muscle have been 



PROTECTIVE RESEMBLANCE 



13 



described as belonging to them. It is evident that the sponge 
possesses irritability and contractility. It has the instincts of 
self-preservation and of the perpetuation of its species. No one 
can correctly interpret the psychologic phenomena of any 
animal until he has passed through the same psychic phenomena 
as that animal, and then become a man with the memory of 
these experiences and what they signified to that animal. Since 
we cannot do that, we must be content to iiifer the significance 
of certain biologic phenomena from comparison with our own 
experiences. 

Environment. — As has been said, sponges are greatly in- 
fluenced as to their shape by the objects to which they are at- 




Fig. 6. — A young sponge. (After Burnet.) 

tached and by the depth and currents of the water. They are 
much more nearly uniform in deeper waters. The plastic 
sponge well illustrates the influence of gravity (geotropism) 
upon an animal. It also shows rheotropism} 

Protective Resemblance. — Their protective resemblance is 
exceedingly good. They look so much like the seaweed and 
other aquatic vegetation that they are well concealed from 
the animals which prey upon them, such as worms, crustaceans, 
mollusks, and other marine invertebrates. Their tough, horny 
texture and their silicious or calcareous spicules are also a 
means of protection. Their characteristic odor, said to re- 
semble garlic, makes them distasteful to fishes. 

^ See Glossary. 



14 



BRANCH FORIFERA 



Symbiosis. — Examples of symbiosis are found among them, 
as that of the sponge and the crab. The sponge attached to the 
crab is carried about by it and given better opportunity of ob- 
taining food and oxygen, while the crab, in turn, is concealed 
from its enemies by the sponge. In the fresh-water sponge, a 
green alga sometimes grows, giving the green color to the mass. 

Various small marine forms are found in the sponges, giving 
good examples of commensalism. Sponges are never parasitic. 




Fig. 7. — Spongers at work. The " sponge hook " is a three-toothed 
curved hook attached to a pole, the length of which varies with the depth 
of the water. The sponge-glass is a common water-pail with the bottom 
knocked out and a pane of window glass put in its place. If is used for 
seeing below the surface where the water is disturbed by ripples. (Cobb, 
in Circular 53.5, U. S. F. C, 1902.) 



Use, — They are of use as food for other animals, and their 
skeletons form a very useful article of commerce. 

The sponges of shallow water are obtained by men in boats, 
with a dredge or a long-handled hook or rake (Fig. 7) ; those of 
the deeper waters, by divers. They are then exposed to the 
air for a time and then heaped up in water again in tanks 



CLASSIFICATION 



15 



provided for them, where they decay. The animal matter 
in them is " beaten, squeezed, or washed out," and their 
skeletons sent to market (Fig. 9). 

Geographic Distribution. — Fresh-water sponges are found 
in streams and lakes in all the continents. Marine forms 
are found in all seas and in all depths, from the shore between 
tide-marks to the deepest abysses of the ocean. They are most 
abundant in tropical waters. 

Geologic Distribution. — Silicious sponges were not uncommon 
in the Cambrian Period, and are found in the formations from 




Fig. S. — Bringing sponges from the vessels to sponge wharf at Key West. 
(Report U. S. F. C, 1902.) 



that time on. They were abundant in the Jurassic and very 
abundant in the Cretaceous of Europe; none have been found 
in that of America. 

Important Biologic Facts. — Even in this low type there is a 
differentiation of certain cells for certain purposes, as the 
skeletal and reproductive cells. True sexual reproduction ap- 
pears for the first time in the Porifera. Conjugation was noted 
in the Paramoecium. 

Classification. — Sponges are of three kinds: (1) The calcar- 
eous sponges, containing much lime. They are of little or 



16 BRANCH PORIFERA 

no commercial value. Example, Grantia. (2) The silicious 
sponges, in which the skeleton is largely silica. Example, 
EuplecteVla. (3) The horny sponges of commerce. Euspongia 
group. To this group belong the half-dozen species of Florida 
and the Mediterranean and the Red Seas. Our American sup- 
ply comes principally from Florida and the Mediterranean Sea 




Fig. 9. — A sponge auction at Anclote. (Report U. S. F. C, 1902). 



from water not exceeding 30 fathoms deep. Examples of this 
group are Spongia, and the fresh-water forms of the genus 
Spongilla. 

Most zoologists make but one class of porifera; others, two 
classes : 

I. Calca'rea. 

II. Non-calca'rea. 



BRANCH CCELENTERATA 

This branch comprises our fresh-water Hydra, and a few 
alhes, and the marine forms, jelly-fishes, corals, and sea-ane- 
mones. This branch finds representatives from the shore line 
and the surface to the profound depths of the ocean. 

The body, which is usually radially symmetric, consists es- 
sentially of a two-layered sac, which is open at one end and 
closed at the other, and in which there is a simple or branched 
gastric cavity. The outer layer is called the ectoderm; the 
inner layer, the endoderm, and a gelatinous non-cellular layer 
between them, the mesoglea. Some coelenterates are soft- 
bodied, others secrete a calcareous or limy substance called 
coral. Around the free open end of the sac-Hke body are a 
varying number of tentacles. 

Nettle Cells. — Stinging or nettle cells are characteristic of 
this branch, except in Cetenoph'ora, where they are replaced 
by adhesive cells. These stinging cells, which are especially 
abundant on the tentacles, contain a fluid, and a spirally wound 
thread provided with barbs, which, when the animal is disturbed, 
are discharged into the body of the intruder, paralyzing it. It 
is then seized by the tentacles and drawn into the mouth. 

Size. — Coelenterates vary in size from the little fresh-water 
hydra, a fraction of an inch in length and of the diameter of a 
pin, to the giant jelly-fishes, as the Cya'nea, which sometimes 
reach 7 or 8 feet in diameter and have tentacles more than 100 
feet long. 

Locomotion. — Some members of this branch are free, as the 
jelly-fishes; some are permanently fixed; as the Corals, while 
some, as the Hydras, are temporarily fixed, moving from one 
position only to adhere to another, and thus making slow pro- 
gression. 

Multiplication is both sexual (by eggs) and asexual (by 
budding) . 

Origin. — ^They are of ancient origin, being abundant in the 
Cambrian Period. 

2 17 



18 



BRANCH CCELENTERATA 



CLASS I. HYDROZOA 

In this class are found the worldwide fresh-water Hydras and 
the marine Hydroid Colonies, such as Campanula'ria or Ohe'lia. 

The Hydras are small fresh- water Hydrozo'a from i to J or 
possibly I inch in length. They may be white or colorless, or 
green or brown. 

The body is a simple cyhnder (Fig. 10) or sac, closed at one 
end, and near the other surrounded by six or eight tentacles, 




Fig. 10. — Hydra: Longitudinal section of animal, showing m, mouth; 
t, tentacle; d, digestive cavity; h, bud; s, spermary; o, ovary; ec, ectoderm; 
en, endoderm. Magnified. (From Dodge's "General Zoology," American 
Book Co., Pubhshers.) 



above which is the conical hypostome, at the apex of which is the 
mouth. The muscular fibers of the ectoderm extend lengthwise, 
while those of the endoderm extend around the body.^ If 
disturbed, the Hydras protect themselves by withdrawing into 
a tiny sphere, while the tentacles contract until they look like 
so many small buds. The endoderm has flagellate cells lining 
the gastrovascular cavity. 

^Hertwig's "Manual of Zoology," Kingsley, p. ^30. 



HYDROZOA 19 

The food is obtained by the viscid tentacles, which, when the 
Hydra is undisturbed, are extended (as is usually the body), 
ready to grasp the prey, for this tiny animal is carnivorous, 
feeding upon small organisms, usually crustaceans. There are 
nettle cells, or nematocysts, in the ectoderm of the tentacles. 
When an animal comes in contact with a tentacle, the nemato- 
cysts near the point touched throw out stinging threads which 
partially paralyze the animal by the fluid which they discharge 
into the wound they have pierced. The tentacles then pass 
the prey to the mouth, which opens into the gastrovascular 
cavity, in which digestion is carried on and into which the 
wastes are gathered and thrown out through the only opening, 
the mouth. The Hydra, by its wide-open mouth and envelop- 
ing lips, often takes in organisms much larger than itself. 

Nerve-cells, sex-cells, and nettle-cells are situated in the 
ectoderm. 

Multiplication in the Hydra is both sexual and asexual. 
It reproduces by budding, but as the buds mature they become 
detached, so that no permanent colony is formed. It also 
reproduces by eggs, the animal being hermaphroditic, that is, 
the reproductive organs of both sexes are found in the same indi- 
vidual. Near the base of the tentacles are found the spermaries 
from which the sperm cells are discharged into the water; the 
ovaries are situated farther down, near the lower end of the 
body. The eggs are cross-fertilized, that' is, fertilized by the 
sperm cells of another individual. After fertilization the ova 
remain in the ectoderm for some time, when they become en- 
cysted in spiny cysts, drop off into the water, and sink to the 
bottom. They lie here till the following spring, when they 
break their casing and come forth as minute Hydras. In the 
encysted condition they are able to withstand cold and drouth, 
thus insuring the perpetuation of the species. Hydras also have 
the power of regenerating the whole body from a part in case of 
injury. 

Locomotion. — The Hydra is temporarily fixed by adhering 
to the submerged stems of water plants by means of a sticky 
secretion from the closed end of the tube. It can detach itself, 
and, by grasping with its tentacles, can pull itself up and again 
attach the end of its tubular body to an object. By this cater- 



20 



BRANCH CCELENTERATA 



pillar-like looping it is able to change its position or perform 
slight locomotion. 

Dispersal. — While the mature Hydra has very limited powers 
of locomotion, or direct dispersal, its offspring may be widely 




Fig. 11. — A, Part of the colony of Bougainvil'lea mus'cus, one of the com- 
pound Hydrozoa, of the natural size. B, Part of the same enlarged: p, A 
polypite fully expanded; m, an incompletely developed reproductive bud; 
ni', a more completely developed reproductive bud; /, coenosarc with its 
investing periderm and central canal. C, A free reproductive bud or medu- 
siform gonophore of the same: n, Gonocalyx; p, manubrium; c, one of the 
radiating gastrovascular canals; o, ocellus; v, velum; t, tentacle. (After 
AUman.) 



separated from the parent through indirect dispersal, or the 
drifting about of the encysted eggs by means of currents and 



HYDROZOA 21 

waves, or the transporting, by the same means, of the debris 
to which they are attached in later hfe. 

Symbiosis is exemplified by Hyd'ra vir'idis, or the green 
Hydra, the color probably being due to the presence of small 
green algce. 

Another species found in Russia, Polypo'dium hydrifor'me, 
of which little is known, is parasitic on sturgeon eggs.^ 

A Hydroid Colony (Fig. 11). — Suppose a hydra-like animal 
to bud and branch until it looked like a tiny bushy shrub. This 
will give you some idea of these plant-like hydroids. These 
hydra-like animals, or polyps, are connected by a system of 
tubes, the common stem or axis bearing many individual zooids. 





Fig. 12. — Obe'lia flabella'ta. (Hincks.) Fig. 13. — Obe'lia conmiissura'lis. 

Obelia (Figs. 12, 13) is a good representative of such colonies. 
The axis is made up of a creeping horizontal portion and of 
vertical axes. The short, alternate, lateral branches of these 
axes bear zooids at their extremities, or, again branching, the 
polyps or zooids are borne on the second set of branches. When 
these zooids are immature, they are little, club-shaped enlarge- 
ments. When mature, the polyps are surrounded proximally by 
a little glassy, protective cup, the hydrotheca, and distally bear 
about a score of tentacles. These are the nutritive zooids, 
for division of labor is found here. The tentacle-bearing indi- 
viduals procure the food, and since the tubes are all hollow 

^ Hertwig's " Manual of Zoology," Kingsley, p. 241. 



22 BRANCH CCELENTERATA 

and connected, the whole colony shares the food thus supplied. 
When disturbed the polyp withdraws into the hydrotheca for 
protection. 

Blastostyles. — But while the majority of the members of this 
colony are hydra-like, tentacle-bearing polyps which reproduce 
by budding only, and can enlarge the original colony, they 
have no power of directly producing a new colony in a more 
favorable position. There is, therefore, another set of individ- 
uals (see Fig. 11). These, while forming a part of this tubular 
colony, are modified in their form for a particular function. 
They are situated toward the proximal region of the colony and 
are long, cylindric bodies, known as blastostyles, each of which is 
enclosed in a transparent case, the gonotheca. These are the 
reproductive zooids, and bear small lateral circular buds called 
medusa buds, which, as they mature, become detached and pass 
out through an opening now formed at the end of the gonotheca. 

Alternation of Generations. — These medusa buds are sexual 
and dioecious, i. e., the sexes are separate, one individual producing 
the ova and another the sperm cells. After fertilization, which 
takes place in the water, the egg develops into a simple, free- 
swimming ciliated larva, the planula, which soon attaches itself 
to some object, develops into a polyp, and, by budding, forms 
a new colony. This regular reproduction by budding, and then 
by eggs, and then by budding again is called alternation of genera- 
tions, or metagenesis. 

Medusae. — Careful study shows that the Medusa is only a 
highly developed or modified zooid. The cylindric body has 
been developed into a disk or umbrella-shaped body (Fig. 14) ; 
the long axis has been greatly shortened and is suspended be- 
neath the center of the sub-umbrella, as the under surface of 
the disk is called, where it takes the name of manubrium, or 
" handle." At the free end of this manubrium is the mouth, 
which opens into the gastric cavity that occupies the whole 
interior of the handle. 

At the base of the manubrium four radial canals, equally 
distant from each other, are sent out to the circular canal, 
which runs around the margin of the umbrella, but within its 
substance. Thus, the food taken into the mouth is distributed 
to the whole animal. The whole canal system is lined by endo- 



HYDROZOA 



23 



derm, which is ciHated. The endoderm also forms the axes 
of the tentacles. There is also a layer of endoderm between the 
radial canals extending from the circular canal to the gastric 
cavity. Between the endoderm and the ectoderm, which 
covers the convex surface or ex-umbrella, is a much-thickened 
jelly-like mass of the mesoglea, while between the endoderm 
and the ectoderm covering the sub-umbrella there is a thin 
layer of mesoglea. The ectoderm, of course, covers the tenta- 
cles, where it is well supplied with stinging cells. At the margin 
the ectoderm of both the sub- and ex-umbrellas forms a narrow 







/ 

Fig. 14. 



1 2 

-1, Pela'gia panopy'ra, oral view of mature medusa. 2. The same, 
side view. (Mayer, in Bull. U. S. F. C, 1903.) 



fold or shelf, the velum, which hangs down when at rest, but 
draws up like a diaphragm across the bottom of the umbrella 
when the bell contracts. By the forcing out of the water the 
animal is forced forward, and so locomotion is effected. Around 
the outside of the velum is a row of tentacles, usually four or 
some multiple of four in number. 

Muscles of a longitudinal character control the tentacles, 
while circular striped muscles surround the sub-umbrella and 
velum, and, by contracting the umbrella and velum, produce 
locomotion. 



24 



BRANCH CCELENTERATA 



The nerve ring surrounds the margin between the circular 
muscles of the umbrella and those of the velum. At the bases 
of two of the tentacles of each quadrant there are sense organs. 
They probably aid the medusa in determining in what direction, 
with regard to the vertical, it is swimming, that is, whether it is 
moving up, down, or sidewise. In other medusae the simplest 
of eyes, red pigment spots, which may or may not have a lens, 
are found. 

The food of the medusa consists of both plants and animals. 
It is very voracious and grows rapidly after leaving the colony. 




c. a- ^ 

Fig. 15. — Hydractin'ia polycli'na: a, Nutritive individual; b, reproduc- 
tive individual; c, spiral zooids or fighting individuals. (Bull. 455, U. S. 
F. C.) 

Multiplication. — After a time either eggs or sperm cells 
develop, and are set free in the water, where they unite with 
those of some other medusa and develop into the tiny larval 
form, which soon attaches itself and grows into a hydroid, to 
bud and branch and produce again the medusae, thus repeating 
the life-cycle and the reproduction by alternation of genera- 
tions. 

There are more than a thousand species of the class Hydrozoa. In 
some forms (Fig. 15), as the Hy'dractin'ia, there are several classes of 
individuals — the nutritive, the defensive, and the reproductive — with 



HYDROZOA 



25 



the corresponding division of labor. These Hydraclin'ia live upon the 
surface of the shells of sea-snails or whelks, which are inhabited by hermit 
crabs, and afford another good example 
of symbiosis. The Hydractinia gets 
free transportation, aiding it in secur- 
ing food; it also probably feeds upon 
minute fragments of the crab's food; 
while the crab, in turn, is protected 
from intruders by the stinging cells of 
the Hydractinia. If the hydroids are 
in any way torn from the shell, the crab 
finds another colony, and, tearing it 
loose from its supporting object, places 
it upon its borrowed shell. 

Millep'ora alcicor'nis is a species of 
so-called hydroid " corals " — the beau- 
tiful elk-horn or stag-horn coral of 
Florida. The permanent colony num- 
bers thousands of individuals, which 
differ in their structure according to 
their division of labor. Their cal- 
careous skeletons are a cuticular prod- 
uct of the ectoderm. 

Another order of the class of 
Hydrozoa is characterized by a 
closed float containing air or gas 
which serves to keep the colony 
vertical in the water. In the 
" Portuguese man-of-war " (Fig. 
16), found as far north as New 
England, there are suspended 
from the large float (3 to 12 cm.)^ 
peacock blue, or, in some cases, 
orange in color, several kinds of 
individuals; some of them, many 
feet in length and armed with 
nettle cells, capture the food and 
bear it to the mouth-bearing or 
nutritive polyps, which digest the 
food and distribute it to the col- 
ony. Others, the feelers, are groups of deep blue medusoids re^ 
sembling bunches of grapes, while others, with swimming move 
ments, aided by the wind, drive the colony from place to place 




Fig. 16. — A Portuguese man- 
of-war (Physalia), with man-of- 
war fishes ( Norneus gronovii) liv- 
ing in the shelter of the stinging 
feelers. Specimens from off 
Tampa, Fla. (From Jordan and 
Kellogg, " Animal Life," D. 
Appleton and Co., Publishers.) 



^ Parker and Haswell. 



26 BRANCH CCELENTERATA 



CLASS II. THE SCYPHOZO'A 



Jelly-fishes are soft umbrella-like creatures resembling molds 
of jelly or gelatin, as one sees who picks them up along the beach, 
where they have been cast ashore by the waves. Their tissues 
are very watery, hence the scarcity of their fossil remains. 
However, very perfect impressions of jelly-fishes are found in 
the upper Jurassic Period. Most jelly-fishes are marine and 
free swimming, though a few are temporarily attached. They 
are most abundant in the tropics. Great schools of them are 
sometimes seen. Sometimes they are phosphorescent. They 
vary in size from about 4 mm., in the simple little, bell-hke 
Tessera, to 1 foot in the Aurelia, and 7 or 8 feet in diameter in 
the Cyanea, whose tentacles sometimes reach the length of 
130 feet. A small form, Gonionemus, found at Wood's HoU, 
Mass., is green and about 1 inch in diameter. It grows on eel- 
grass. All are carnivorous, feeding mostly upon crustaceans, 
though some of the larger ones capture fishes of considerable size. 

The food is captured by the tentacles, which are suspended 
from the margin of the umbrella and which are armed with 
stinging thread cells. 

Locomotion is effected by the flapping of the umbrella-Uke 
body, there being usually no velum. 

Minute colored " eye-specks " are around the rim. 

Multiplication usually is by alternation of generations, but 
the young medusa or ephyra, as it is called, undergoes a meta- 
morphosis or change of form as it matures. In some cases the 
egg develops directly into the larval medusa and there is no 
alternation of generations, but simple metamorphosis. 

CLASS III. ACTINOZO'A 

This class includes sea-anemones, sea-pens, and corals. 
Only the polyp form is found in this class, no medusa being 
known among them. They are exclusively marine. They are 
usually fixed and many form permanent colonies. 

One point in their development is a step in advance of the 
Hydrozoa, i. e., the development of a gullet, esophagus, or 
stomodceum, the beginning of which is seen in the Scyphozoa. 
The hypostome, which in Hydrozoa bore the mouth at its apex, 



ACTINOZOA 



27 



is here inflected and forms a tube dipping down into the body 
cavity, Imt not reacliing tlie bottom of it. The lower end of this 
tube or esophagus (which is really the beginning of the ali- 
mentary tube of higher animals) corresponds to the mouth of 
the Hydra, so that the tube is lined with ectoderm. The mouth 
is the only external organ, and serves both for the entrance of 
food and the ejection of waste. The body cavity about this 
tube is divided by thin partitions into radiating spaces. 

No actinozoan is microscopic. All are long lived. One in an 
English aquarium lived more than sixty years. ^ The sea-ane- 
mones and all true corals producing reefs and islands have the 
number of their tentacles in multiples of six. 



««;#-- 




Fig. 17. — Sea-anemone [Metrid'ium). (Emerton.) 



The Sea-anemones (Fig. 17). — As one gazes in wonder at 
the sea-anemones in their marine home, he can scarcely persuade 
himself that those beautifully colored objects, so flower-like — 
hollow cups with their petals and sepals of such wonderful tints 
— are else than flowers. But he touches one, the " sepals and 
petals " close in upon his fingers, they tingle, and he finds that 
this flower-like object is an animal and that the " sepals and 
petals " are tentacles. A very different appearance it makes 
when the body has been dra-^ni down close to its attachment by 
the longitudinal muscles, while the circular muscles shut in the 
1" General Zoology," Dodge, p. 75. 



28 



BRANCH CCELENTERATA 




Fie. 18. — Athe'Iia mirab'ilis. General view of branch. View of a calice. 
(Vaughan, in Bull. U. S. F. C, 1900.) 




Fig. 19. — Favia fragum (Esper). View of a corallum from the side. 
(Vaughan, in Bull. U. S. F. C, 1900.) 



retracted tentacles until it looks like a round mass of flesh. The 
tentacles are hollow and are armed with lasso cells, which are 



ACTINOZOA 



29 



useful not only for defense, but for capturing crabs and small 
fishes which form the anemone's food. 

Sea-anemones are solitary, that is, they form no permanent 
colony. They have no true skeleton. There is no alternation 
of generations. They vary in size from i inch to 2 feet in 
diameter, and, though attached, have the power of changing 
their position. 

The Stony Corals (Fig. 18). — The coral polyps resemble small 
sea-anemones on a much-branched stem. The calcareous skele- 




Fig. 20. — Isovo'ra murica'ta forma prolif'era lam. End of branch, height 
9 cm. (Vaughan, U. S. F. C. Bull., 1900.) 



ton is secreted by the ectoderm. The branched form arises 
from the continual budchng and branching from a parent stem. 
The different forms (Fig. 19) of coral are caused by the different 
modes of budding in the various species. Corals are of various 
colors and some are said to be phosphorescent. 

The members of a coral colony are organically connected. 
Each feeds himself, it is true, but no individual of the colony is 
independent of the others. 

The size varies from that of the head of a pin to | inch, 



30 



BRANCH CCELENTERATA 



the solitary mushroom coral being sometimes of the exceptional 
size of 1 foot in diameter. 

These myriads of coral polyps (Fig. 20) secrete great quanti- 
ties of lime, the waves break off the branches, grind them up, 
mix them with sand and shells, and thus build up coral reefs 
and islands of vast extent. These are confined to warm regions 




A sea-fan. 



about 30 degrees on each side of the equator, since coral colonies 
cannot live in temperature below 60° F., and for a full luxuriance 
a higher temperature is necessary.^ They are also shallow water 
animals, living from the high-water-mark to a depth of not 
more than 20 fathoms. They must also have salt water, hence 
they cannot live at the mouth of a river. 

1 Scott's "Geology." 



CTENOPHORA 



31 



The Octocoral'la, or those forms which have eight tentacles, are found 
in all seas, both in shallow water and at great depths. They include 
the organ-pipe coral, the precious red coral {Corallimn rubrum) of the Medi- 
terranean Sea, and the sea-pens and the sea-fans. The mesoglea of many 
octocoralla contains irregular calcareous spicules. 

The sea-pens (Pennatula'cea) usually form an elongated colony. The 
stem, one end of which is embedded in the sand or mud of the sea bottom, 
is supported by a calcareous or horny skeleton. The distal portion is dis- 
tended like a feather and bears the dimorphic polyps. 




Fig. 22. — Photograph taken with the camera submerged,, to show 
aquatic animals in their natural environment. In the background are seen 
sea-fan and branching gorgonian. (Bull. U. S. B. F., 1907.) 

The sea-fans {Gorgona' cea) (Fig. 21) have a branched colonial axis formed 
of horny or calcareous substance from the ectoderm, with spicules in the 
mesoglea. 

In some cases the skeleton formed by the spicules forms a branched 
axis, as in Corallium rubrum, or it may form a " series of connected tubes 
for the individual, as in the organ-pipe coral {Tubip'ora) ." " The red coral 
is found only in the Mediterranean Sea at a depth of from 10 to 20 fathoms."^ 



CLASS IV. CTENOPHORA 

The Ctenoph'ora, or " comb-jellies," are so-called from 
eight bands of comb4ike cilia fused at their bases, which sur- 
round their nearly transparent bodies. The body is non-con- 

^ Parker and Hasweir."* "Zoology." 



32 BRANCH CCELENTERATA 

tractile, and these cilia accomplish locomotion. They are 
free and single, there being no polyp stage. They are found 
from the tropical to the arctic seas. They are small — from 
5 to 20 mm. in diameter — and their shape varies from that of a 
pear to a sac-like or ribbon-like form. They have but two 
tentacles. They are hermaphroditic, multiplying by eggs. 

The central nervous system is represented by a ciliated area 
on the aboral pole, and is connected with a single sensory 
organ. 

Economic Value. — The animals of this branch are of great 
use to man, indirectly, by furnishing food for other animals, and, 
directly, by the formation of great beds of limestone and of 
coral reefs and islands, also by forming an article of commerce 
of no small value.^ 

" The red coral of commerce is obtained in the Mediterranean 
Sea off the coast of Africa and the west coast of Italy. The price 
varies according to the color. The finest rose pink in large 
pieces is valued at $400 or more an ounce. The common 
article brings from $1 to $1.50 an ounce. "^ 

Geologic Distribution. — The hydrozoa are believed to be 
represented by the Graptolites, which appeared in the Cambrian 
Period, were numerous in the Ordovician, greatly diminished in 
the Silurian, and almost extinct in the Devonian. Large 
numbers of casts of jelly-fishes are found in the Cambrian rocks.'* 
Hydroids and true corals were important. Marine life and reefs 
were formed in the Silurian Period. Corals vastly increased 
in size and number in the Devonian Period, and were abundant 
in the Carboniferous, contributing largely to the limestone. 
Hydractinia were found in the Cretaceous Period. 

Important Biologic Facts. — In the Ctenophora is found for the 
first time a true middle layer of mesoderm cells. ^ 

In the hydroid colony is found the division of labor among 
the different sets of individual zooids and a differentiation of 
structure according to their function. 

1 " The fishing for the red coral {Cor allium, rubrum) at Naples amounts 
yearly to half a million dollars." — Kingsley. 

2 Adam's "Commercial Geography." 

3 Scott's "Geology," p. 371. 

* Parker and Haswell's "Zoology," vol. i, p. 207. 



CTENOPHORA 



33 



Classification. — 

Class. 
I. Hydrozo'a. 
II. Scyphozo'a, 

III. Actinozo'a. 

IV. Ctenoph'ora. 
3 



Examples. 
HyMra, Hydroid Colonies. 
Jelly-fishes. 

Sea Anemones and Coral Polyps. 
"Comb-jellies." 



BRANCH PLATYHELMINTHES 

Platyhelmin'thes, or Flat Worms, have three germ layers, 
the ectoderm, the mesoderm, and the endoderm. They are 
flattened dorsoventrally and are bilaterally symmetric. They 
have no skeleton, no circulatory system, and no coelom or body 
cavity. They have an anterior and a 'posterior end, but rarely a 
distinct head. 

The nervous system is composed of superesophageal ganglia 
and lateral nerve-trunks. 

The excretory system consists of water-vascular tubes. 
There is no anal opening. 

Development is sometimes with and sometimes without a 
metamorphosis . 

Habitat. — Some, as the liver-fluke and the tapeworm, are 
parasitic; others, as Planaria, live in fresh water. Some live 
in moist places or in the mud at the bottom of ponds and 
streams; while others, as Leptoplana, are marine. 

Size. — The parasitic forms are sometimes 30 or 40 feet in 
length, while the free forms are but 2 or 3 inches in length. 
These are often found under stones, and are exceedingly deli- 
cate. 

Protective resemblance is very great in some species, while a 
few are nearly transparent. 

CLASS I. TURBELLARIA 

The class Turbella'ria consists principally of non-parasitic 
forms which are ciliated externally. There is usually a diges- 
tive cavity. The prevailing shape is leaf-form, like that of 
Plana'ria. Some marine forms, however, are shaped like " a 
thin ribbon with puckered edges," others may be thickened and 
band-like, as in the land planarians, while others approach the 
shape of a cylinder. Locomotion is performed by the fine 
vibratile cilia which cover the surface. The ectoderm contains 
sensory and gland-cells. 

34 



TREMATODA 



35 



CLASS II. TREMATODA 
The class Tremato'da is comprised of worms either internally 
or externally parasitic. The body is usually thicker than that 

of the turbellarians. The 
form is usually leaf-like, 
■ though it is sometimes elon- 
gated. The anterior end is 
distinguished by the arrange- 
ment of suckers, and, in some 
of the external parasites, by 
eyes. 




Fig. 23. — The common liver-fluke 
(Fasci'ola hepat'ica) enlarged to show 
the anatomic characters : ac, Acetab- 
ulum; c, p., cirrus pouch ; i, intestinal 
ceca; m, mouth with oral sucker; ov, 
ovary; p. b., pharyngeal bulb; s. g., 
shell gland; t, profusely branched 
testicles; ut, uterus; va, vagina; 
V. g., profusely branched vitellogene 
gland. (After Stiles, 1894, p. 300.) 




Fig. 24. — Embryo of the com- 
mon liver-fluke {Fasciola hepalica) 
boring into a snail — x 370. (After 
Thomas, 1883, p. 285.) 



The suckers are organs of adhesion and are sometimes armed 
with bristles or hooks. They are also used in locomotion, which 
is a sort of looping, like that of the leech. Except in two cases 
the vibratile cilia are not found on the surface. 



36 



BRANCH PLATYHELMINTHES 



The trematodes are hermaphroditic, and the development may 
be either with or without a metamorphosis. 

The Liver-fluke (Fig. 23) is parasitic in sheep. The eggs pass down the 
bile-ducts of the sheep into the intestine, and from there to the exterior, 
when the embryo escapes by the separating of the Ud, or operculum, from 
the egg-shell. 

The ciliated larva swims about in the water 
or remains in the damp vegetation until it 
comes in contact with a pond or land snail 
(Fig. 24). It then bores into the body of the 
snail, where it develops into a sporocyst 
(Fig. 25), which produces redice. These redioE 
possess a mouth, a pharynx, an intestine, and 
an opening for the escape of the young, which 
are internally produced. According to the 
season, these young are cercarim or redice, 
several generations of which may follow 
before the cercarice appear. The cercarice are 
adapted for aquatic life. 





Fig. 25. — Sporocyst of the com- Fig. 26. — Free-swimming cercaria 

mon liver-fluke from the body of a of the common liver-fluke, greatly 
snail, containing redise in course of enlarged. (After Leuckart.) 
development — enlarged 200 times. 
(After Leuckart.) 

The cercarice (Fig. 26) escape from the snail, swim about with their vibra- 
tile tails for a time, when the tails drop off and the cercarice become encysted 
on a plant. When this plant is eaten by a sheep, cow, or hog, the young 
escapes from the cyst and makes its way up the bile-ducts to the liver, 
where it develops into the mature worm and produces reproductive organs, 
thus completing the life-cycle. 

Sheep pastured in swampy places are likely to be infected by this para- 
site, and wet seasons cause epidemics. 



CESTODA 



37 



In England the annual loss of sheep killed by the liver-flukes is estimated 
at $1,000,000, and it has been known to reach $3,000,000 in one year. 
There have been a few cases of this parasite found in man. 

CLASS III. CESTODA 

A tapeworm (Tce'nia so'lium) is a parasite in the intestine 
of man. It is ribbon shaped (Fig. 27), being much narrower at 
the attached end, the head, or scolex. 

The scolex is knob-shaped and bears the organs of attach- 
ment, a circle of hooks at the end, and a sucking disk or cup- 
shaped sucker on eacH of the four sides. The attachment is 
temporary. 

.^IIIIHiiJimiJiii'i-m'niiirmTTTn ^Fi 




Fig. 27. — Tce'nia sagma'ta. (Eichhorst.) 



Segments. — The remainder of the tapeworm, except a short 
portion immediately posterior to the head, is made up of a series 
of segments or -proglottides, the number of which varies in differ- 
ent species. In Taenia solium there are about eight hundred and 
fifty segments, while in the smaller species there are three or four 
hundred, and in the larger species, several thousand. These 
segments or proglottides are derived from the head by a kind 
of budding. Thus it is that so long as the head remains the 
tapeworm continues to grow. 

Digestion. — There is no digestive system, the nutrition 
simply being absorbed from the liquids of the host. 

The nervous system consists of a pair of ganglia, from which 
two main nerve-cords extend back through the length of the 
worm. 

The excretory or water-vascular system consists usually of 



38 



BRANCH PLATYHELMINTHES 



four principal trunks extending throughout the scolex and 
proglottides. 

Multiplication and Development. — Each proglottis, as it 
matures, becomes hermaphroditic. Since these proglottides 
are originally developed from the head, the posterior ones are 
oldest. When filled with embryos, they are detached and pass 
out with the waste material from the intestine. When taken 
into the alimentary canal of the hog with its food, the hooked 
embryos bore through the intestinal wall and into the voluntary 
muscles, where they grow and 
continue to develop until they 





Fig. 28 — Taenia echinococ'cus, en- Fig. 29. — Portion of the intestine 

larged. (Mosler and Peiper.) of a dog infested with echinococcus 

tapeworms, natural size. (Oster- 

tag.) 

reach the bladder-worm stage, or cysticercus. When pork 
containing a cysticercus is eaten, unless it has been killed by 
thorough cooking, the head is everted from the bladder-like 
covering and is attached to the intestinal wall of the host, 
where proglottides are rapidly developed. These mature in 
ten or twelve weeks. 

Species. — There are many species of tapeworms. One form, 
Tcenia saginata, which occurs in man, is obtained through 
eating beef cooked rare; another form, Tcenia solium,^ already 
mentioned, from eating pork; and another, Bothrioceph'alus 

1 Tcenia solium is sometimes found in the encysted or intermediate stage 
in the muscles, eye, or brain of man. The eggs are thought to have been 
taken into the stomach with lettuce, cress, and the like, which had been 
watered with liquid manure. 



NEMERTINEA 



59 



latus, from eating fish. The latter species is the largest tape- 
worm found in man and sometimes reaches a length of 40 feet, 
and is composed of more than four thousand proglottides. It 
is rare in America, but is abundant in Russia, Switzerland, and 
the eastern provinces' of Prussia. Another form (Fig. 28), 
perhaps the most formidable, is a small one, Tce'nia echinococ'cus, 
which lives, in the adult stage, in dogs (Fig. 29), and the eggs 
are easily taken into the human stomach by a person fondling 
and kissing infested dogs. The embryos (Fig. 30), when set 




Pig 30 — Portion of hog's liver infested with echinococcus bladder-worm. 

(Stiles.) 

free, work their way into the liver, lungs, brain, or other organs, 
and produce tumors which sometimes reach a large size . Several 
species are found in domestic birds, one causing epidemics 
among chickens. A variety of Toe'nia coenu'rus, in the brain of 
sheep, causes " staggers." Rabbits, horses, cats, mice, and 
rats are also infested by tapeworms. 

CLASS IV. NEMERTINEA 

(Doubtful Platyhelminthes) 

The Nemertineans are most abundant in the mud or under 
stones along the seashore, only a few species living in fresh 
water. They differ from all other Platyhelminthes in having 



40 . BKANCH PLATYHELMINTHES 

an alimentary tract with an anal opening and a distinct blood- 
vascular system.^ They are usually dioecious.^ 

Geographic Distribution.- — This branch of animals is the most 
widely distributed of any above the protozoans. They are 
found on land, in streams, and in the depths of lake and sea. 
The parasitic forms are found in some stage in almost every class 
of metazoans, while others have a commensal hfe with ascidians. 
All are carnivorous. 

Economic Importance. — Many domestic animals are hosts 
for these parasites and much loss is occasioned thereby. A 
number of class Cestoda are parasitic in man and cause annoy- 
ing if not dangerous diseases. The only sure preventive of these 
parasites is to have all meats thoroughly cooked and fruits and 
vegetables well washed. 

Important Biologic Facts. — An anterior end — one placed 
foremost in locomotion — and a posterior end appear for the first 
time in platyhelminthes. Also right and left and dorsal and 
ventral sides are found. 

In the Nemertinea there is an alimentary tract with a mouth 
and an anal opening. There is no distinct coelom. 

Class Turbellaria is the most primitive and the most closely 
related to the Ccelenterates, but it is not thought to be derived 
from them, though it shows special points of resemblance to the 
Ctenophora. It is thought that Trematoda and Cestoda are 
descendants of Turbellaria. In Trematoda is seen an alterna- 
tion of generations consisting of the succession of several dis- 
tinct generations in regular series. Such an alternation of gen- 
erations is termed heterogeny. The simple structure of parasitic 
forms illustrates the principle that easy life — one requiring 
little exertion — is accompanied by a low stage of development. 

Classification. — 

Class. Examples. 

I. Turbella'ria. Planarians. 

II. Tremato'da. Liver-fluke. 

III. Cesto'da. Tapeworms. 

IV. Nemertin'ea. Carinella, Tetrastemma, etc. 

1 McMurrich, p. 160; Osborn's "Economic Zoology," p. 85; Kingsley's 
Hertwig, p. 289. 

2 "Invertebrate Zoology," McMurrich, p. 162; Parker and Haswell, p. 279. 



BRANCH NEMATHELMIN'THES 

Round- or Thread-worms. — The worms of this branch are 
elongated and cyhndric and have a ccelom or body cavity. 
The vinegar-eel affords a good example. They differ from 
annelids in that they are not divided into segments or rings. 

CLASS I. NEMATODA 

The members of class Nemato'da are best known as para- 
sites, but there are many fresh-water and marine forms. 

The tough body wall encloses a body cavity which surrounds 
a straight alimentary tube having a terminal mouth and a 
ventral anal opening. An excretory system is usually present. 
The nervous system consists of an esophageal nerve ring which 
sends out six nerves anteriorly and six posteriorly. The only 
sense organs are sensory papillae on the lips. The sexes are 
usually separate. Many of the aquatic forms are free. Some 
of the parasites infect plants, as Tylen'chus trit'ici, which does 
great damage to wheat, and Heterode'ra schach'tii, to turnips in 
Europe. 

One form, Ascaris nigrovenosa,^ living a parasitic life in the lungs of 
frogs and toads, is hermaphroditic. The embryos reach the alimentary 
canal and pass out with the waste material. In water they develop into 
a stage in which the sexes are separate. The eggs develop in the body of 
the female and devour the entire substance of the tissue of the mother, 
leaving only the cuticle. When set free they live in the mud until they 
are taken into the mouth of a frog, when they pass into the lungs and 
develop into the hermaphroditic stage. Here, again, is a peculiar alterna- 
tion of generations (heterogeny), the alternation of an hermaphroditic with 
a dioecious form. 

TrichineFla spira^Iis (Fig. 31) is another member of this class. In the 
adult stage it lives in the alimentary canal of man or of other mammals. 
The length of the adult male is about jV inch, and that of the female about 
I inch. The sexes are separate. The young, at least one thousand, are 
born alive. The young worms (Figs. 32, 33) pass through the intestinal 
wall and make their way to the voluntary muscles, where they penetrate 
the sarcolemma and become encysted. 

^ Parker and Haswell, vol. i., p. 286. McMurrich, p. 176. 

41 



42 



BRANCH NEMATHELMINTHES 




embA 



Fig. 32.— Larvae of Trichinella spiralis in mus- 
cle, not yet encysted ; enlarged. (Leuckart.) 




Fig. 33. — Piece of pork showing larvae of 
Trichinella spiralis encysted in the muscle- 
fibers; natural size. (Ostertag.) 



Fig. 31. — Trichinella 
spiralis. Adult female, 
showing embryos, emb., in 
uterus; gp., genital open- 
ing through which the 
embryos are discharged; 
enlarged. (Leuckart.) 




Fig. 34. — Encysted larva of Trichinella spira- 
lis; enlarged. (Leuckart.) 



NEMATODA 



43 



When the infested flesh, unless thoroughly cooked, is eaten by man the 
cysts are dissolved, the young entering the small intestine, the worms con- 
tinue developing and become sexually mature in a few days, the female 
penetrates into the superficial layer of the intestinal villi, and in the course 
of a month gives birth to young, and then dies. The young wander 
through the lymph-vessels and blood-vessels into the capillaries, pass into 
the muscle and become encysted (Fig. 34) , as did the parents in the former 
host; 1 ounce of infested pork, unless thoroughly cooked, may liberate 
80,000 worms. If half of these were females, each producing 1000 embryos, 
40,000,000 worms would shortly begin to migrate into the muscles, causing 
trichinosis, which may be fatal. The worst epidemic known was in Emmers 
Leben, Saxony, in 1884, where 364 persons were infected from eating one 
pig, and 57 persons died within a month. 

The Guinea-worm {DracmVculus medinen^ sis) is an East India parasite 
in the subcutaneous connective tissue of man. It is long and slender, 
sometimes 1 yard long. It forms abscesses under the skin. When the 
newborn young pass out of their host, if they pass into water, they enter 
the body of a small crustacean (the Cy- 
clops), which is necessary to their develop- 
ment. It is supposed that they reach 
the human system through the Cyclops, 
which is swallowed in unfiltered drinking- 
water. 






Fig. 35. — Eggs of the gape-worm 
{Syn'gamus trachea'lis) , one of them 
hatching; enlarged 260 times. 
(After Megnin.) 



Fig. 36. — Windpipe of chicken 
split open to show gape-worms at- 
tached to its inner surface; en- 
larged. (After Megnin.) 



The hook- worm (Neca'tor america'nus), of the Southern United States 
and the West Indies, is thought to have been introduced from Africa by 
slaves. "It is about J to | inch long and about as thick as a small hairpin." 
— Stiles. 

"In hook-worm disease we have ground-itch, tibial ulcer, anemia, inter- 
ference with phvsicai and mental development, and, in bad cases, dirt 
eating."— Stitt, 244. 

Other Species. — There are various other species. Some, as the pin-worm 
{Oxyuris vermicularis) and the round-worm {As'caris lumbricoi'des), are 
parasitic in man. Some are parasitic in other mammals and some in birds. 
One of the latter, Syn'gamus trachea'lis (Fig. 35), about | inch in length, 
causes "gapes" in poultry (Fig. 36). 



44 BRANCH NEMATHELMINTHES 

Gordius, the " hair-worm," is found in watering-troughs and erroneously 
believed by superstitious people or those ignorant of biologic principles to 
be horse hairs transformed into live worms. The larvae are parasitic in 
the grasshopper, the adults live in water. Agassiz tells of experimenting 
with one 18 inches long which was wrapped in and out of its eggs, which 
were rolled up into a ball about the size of a coffee bean. He disentangled 
it and it " sewed " itself through and through the little white mass. Three 
times he separated the worm from its eggs, and each time the process of 
entangling was repeated, convincing Agassiz that there was a definite 
purpose in its attempts, and that even a being so low in the scale of animal 
existence has some dim consciousness of a relation to its offspring. ^ 

He placed a small portion of the egg mass under the microscope, and 
estimated that there were not less than 8,000,000 eggs in the whole mass, 
which, when unwound, made a string 12 feet long. 



CLASS II. ACANTHOCEPHALA 

Most of the class Acan'thoceph'ala are small parasites. The 
chief genus (Echinorhyn'chus) is parasitic in the intestines of 
mammals, birds, reptiles, amphibians, and fishes. The largest 
species is found in the pig, and one species, Echinorhynchus 
hominis, is extremely rare in man. 

CLASS m. CHiETOGNATHA 

This class contains but two genera of curious arrow-shaped 
worms, all but one species of which are pelagic. They are 
hermaphroditic and have three pairs of coelomic pouches, 
" fins," and bristle-like jaws. 

Economic Importance.- — In this branch may be found worms 
which are harmful and those which are helpful to man. Those 
forms like Trichinella spiralis, which are parasitic in man, are 
very injurious. The only preventive upon which it is safe to 
rely is thorough cooking. 

Those forms which infest wheat and turnips are also harmful 
to man, in that they destroy his food; while Gordius, which is 
parasitic in the grasshopper, is indirectly beneficial to man. 

Important Biologic Facts. — For the first time in the scale of 
animal life, a ccelom, or body cavity, appears. It is filled with a 
clear fluid, and through it extends the straight alimentary tube 
which consists of pharynx or stomodeum, an intestine, and a 
rectum. There are no circulatory and no respiratory organs. 

1 "Methods of Study in Natural History," Agassiz, pp. 63, 64. 



CH^TOGNATHA 



45 



This branch presents similarities to both Platyhelminthes 
and Annulata, but the relationship with either is not close. 
Classification. — 



Class. 
I. Nemato'da. 
II. Acan'thoceph'ala.* 
III. Chaetog'natha.^ 



Examples. 
Trichina, Gordius. 
Echinorhynchus. 
Sagitta. 



1 " The affinities of the Acanthocephala and Chaetognatha with the 
Nematoda are somewhat doubtful," Parker and Haswell's "Zoology," vol. 
i, p. 275. 



BRANCH TROCHELMIN'THES 



The animals associated together in this group may have de- 
veloped independently from trochosphere-like ancestors, but 
since they agree in general character- 
istics, they have been regarded by some 
as constituting a well-marked phylum. 
On account of their size they were 
formerly regarded as protozoans, but 
they are multicellular and possess well- 
defined digestive, excretory, nervous, and 
reproductive systems. They have no 
circulatory system. Respiration takes 
place through the surface of the body. 



CLASS I. ROTIFERA 

The Rotif'era (Fig. 37), or ''wheel 
animacules," are many-celled, micro- 
scopic, unsegmented animals, most of 
which are worldwide inhabitants of fresh- 
water ponds and streams, or even of mud- 
puddles and water-troughs. A number 
of forms are marine. 

The anterior end is a retractile disk 
surrounded by cilia, which are locomotive 
organs as well as aids to securing food. 
The mobile tail is often composed of tele- 
scopic rings, rendering it retractile into 
the trunk. The posterior ring of the tail 
frequently has a pair of pincer-like stylets. 
These and the adhesive glands enable 




_ Fig. 37.— A rotifer, 
highly magnified {Hy- 
datina senta) : A , cilia ; 
a, anus; h, contractile 
vesicle; c, water- ves- 
sels; e, ovary; /, gang- 
lion. (From Holder's 
" Elements of Zool- 
ogy," American Book 
Co., Publishers.) 



the rotifer to attach itself to objects. 
There is a coelom. The alimentary tube consists of a ventral 
mouth, an esophagus, a chewing apparatus (mastax), a glandular 
stomach, and an intestine which ends in a dorsal anal opening. 

46 



GASTROTRICHA 47 

The nervous system consists of a dorsal ganglion with which 
are connected one or more eye-spots. There are peculiar tactile 
organs which consist of " rod-like structures tipped with deli- 
cate sensory hairs." There are excretory and reproductive 
organs. 

They are dimorphic (of two forms). The sexes are separate. 
The males are rarer, much smaller, and less highly developed 
than the female. The female lays thin-shelled summer eggs 
of two sizes — the larger developing into females, the smaller into 
males — and thick-shelled winter eggs, which in the spring de- 
velop into females. 

The majority are free swimming, being propelled by the 
trochal disk, but the Bdelloida also have a looping movement 
like that of the leech. 

The rotifers may be dried up in the mud for several months, 
and upon being brought into contact with water they revive, or, 
some think, their contained eggs bring forth live animals. 
When in the dry condition they may be carried long distances on 
the feet of birds or by the wind. 

CLASS II. DINOPHILEA 

These, like the rotifers, are modified trochospheres. They are minute 
and worm-like. They have a prostomium or head, a body of five to eight 
segments, and a short tail. Both the body and the head are ciliated. The 
Dinophilea are marine. In the arrangement of the nephridia in pairs, 
corresponding to the imperfect segments, and in the tendency to seg- 
mentation, they resemble the Annulata. 

CLASS III. GASTROTRICHA 

This class resembles the Rotifera, though the relationship is not close. 
The class comprises a small number of minute fresh-water forms with 
spindle-shaped bodies, flattened ventrally. The dorsal surface bears 
several rows of cuticular processes, while the ventral surface has two rows 
of cilia. 

Classification. — 

Class. Examples. 

I. Rotifera. Brachionus. 

II. Dlnophirea. Dinophilus. 

III. Gastrot'richa. Ichthydium. 



BRANCH MOLLUSCOIDA 

In this branch there is usually a body cavity, with the ali- 
mentary tube suspended by mesenteries. The mouth and anal 
aperture are near together, the dorsal surface being shortened. 
In the adult there is a tentacle-bearing ridge, or lophophore, about 
the mouth, containing a compartment of the body cavity. 
The tentacles are used not only in securing food, but in respira- 
tion. The nervous system consists of one or two ganglia or of a 

nerve ring.^ 

CLASS I. POLYZOA 

MoUuscoi'da, which usually form colonies of zooids by budding, are 
Pulyzo'a. The character of the colony differs, according to the mode of 
budding in the different species and the character of the exoskeleton. It 
varies from a bush-like colony to a calcareous or gelatinous sheet. Each 
zooid has a crown of ciliated tentacles which can be extended or with- 
drawn. They are held together by the common exoskeleton forrned by 
the ectoderm. There is no vascular system. The digestive tract is bent 
like the letter (J, the anal opening being near the mouth, within or just 
outside of the ring of tentacles. The nervous system consists of a gang- 
lion situated between the mouth and the anal opening. Polyzoans are 
usually hermaphroditic. 

CLASS n. PHORONI^DA 

The classification of this group of worm-like forms of the sea is doubtful. 

The worm is covered by a leathery cylindric tube into which it may 
withdraw. The body is unsegmented and bears a crown of tentacles. 
The mouth and anus are close together and are situated at the tentacle- 
bearing end of the body. The body cavity is divided into three chambers. 
There is an alimentary tract and a closed system of blood-vessels contain- 
ing red blood-corpuscles. The central nervous system consists of a horse- 
shoe-shaped nerve ring at the base of the tentacles. The Phoronis is 
hermaphroditic. There is a metamorphosis. 

CLASS m. BRACHIOP^ODA 

Brachiopods are marine and were abundant in former geologic times, 
being very plentiful as early as the Cambrian Period. There are a few 
living species. 

They are enclosed in a bivalve shell (Fig. 38), the valves being dorsal 
and ventral instead of right and left, as in the mollusks. They are at- 
tached to foreign objects by a peduncle or stalk, which passes through the 
larger or ventral valve near the hinge. They do not form colonies. 
^ Parker and Haswell, p. 313. 
48 



BRACHIOPODA 



49 



The shell is only partially filled by the body, and the valves are lined 
by the mantle lobes, whose free edges are bristled. The mantle lobes 
enclose a large mantle cavity. In the body is a spacious coslom, which is 
extended into the mantle lobes. The coelom contains the digestive tract, 
the liver, and the reproductive organs. The latter are chiefly in the 
mantle lobes. The digestive tract, which is bent much as in the Polyzoa, 
consists of gullet, stomach, and intestine. The mouth is surrounded by the 
tentacled lophophore or " arms." The inner surface of the tentacles is 
covered with cilia, which set up currents in the water and sweep minute 
animals and algae into the mouth for food. The heart, usually present, lies 




Fig. 38. — Diagram of a brachiopod: b, Tentacles around mouth, m; i, 
intestine; the shell black, the stalk to the right. (Kingsley's "Compara- 
tive Zoology," Henry Holt & Co., Publishers.) 

dorsal to the stomach, to which it is attached. The nervous system con- 
sists of an esophageal ring. Sense organs are usually wanting in the 
adult. 

Important Biologic Facts. — For the first time, according to 
the classification used, a closed system of blood-vessels and 
red blood-corpuscles are found. 

The digestive tract has been developed into gullet, stomach, 
and intestine, and a liver also appears. 

The Brachiopoda were formerly supposed to belong to branch 
Mollusca. But the valves of the shell are dorsal and ventral, 
not right and left, while the tentacled lophophore, the character 
of the nephridia, and the modified trochosphere larva all tend 
to show relationship with members of branch Molluscoida. 

Classification. — 



Class. 
I. Polyzo'a. 

II. PhoronI'da. 
III. Brachiop'oda. 
4 



Example. 
Bugula avicularia (Bird's-head 

Coralline) . 
Phoronis. 

Magellania. 



BRANCH ECHINODER'MATA 

Plan of Structure. — These animals are characterized by their 
five-rayed or pentameral plan of structure. While the echino- 
derm is radially symmetric, the development shows that it is 
derived from the bilateral type. The larvoe are bilateral. The 




rig. 39. — Solas' ter endeca (small specimen, natural size), oral view. 
(Bulletin, U. S. F. C, 1902.) 



central portion is the disk, from which arms or rays project, as 
seen in the starfish. Close examination will reveal this penta- 
merous plan in the sea-urchin and in the sea-cucumber. For, 
suppose the rays of the starfish were flexed and their edges 
joined, the form of the sea-urchin would appear. Again, 

50 



GEOGRAPHIC DISTRIBUTION 



51 



lengthen the sea-urchin in the direction of the mouth to aboral 
surface, and you have the form of the sea-cucumber. The 
crinoid also reveals this plan, not so clearly defined, but it is to 
be seen by the careful observer. The number of rays varies in 
the starfish, the author having found them with four, six, or 
even as many as twenty-two rays. 




Fig. 40. — 1 and 2, Aniphipholis squamata (adult), aboral and oral views. 
3 and 4, Asterias vulgaris (small specimen), aboral and oral views. (Bul- 
letin, U. S. F. C, 1902.) 



The Skeleton or " Test." — The body wall is composed of a 
thick leathery substance. In the mesoderm, under the epi- 
thelium, calcareous plates arise, many of which are armed with 
spines for protection. They are greatly protected also by their 
resemblance to their environment. 

Geographic Distribution, — All echinoderms are marine, being 
abundant even in the deep sea. They are found in all parts of 
the globe, but are most abundant in the tropics. At the breed- 
ing season most of the free species frequent the shallow waters 



52 



BRANCH ECHINODERMATA 



near the coast, where the ova are fertihzed in the water. Echino- 
derms of the same species are often gregarious. 

The water-vascular system is a marked characteristic of 
echinoderms (Fig. 41). It begins externally with the cal- 




caecim 
muscles of the pyloric caeca 



eye spot '-- 



Fig. 41. — Dissection of a starfish {Asterias sp.). (From Kellogg.) 



careous perforated madreporic plate which is connected by a 
calcareous (Stone) canal with the central ring around the 
mouth, from which tubes proceed along each arm, in the star- 



METAMORPHOSIS 53 

fish. On the inside of the floor of each ray are the ampullce, 
small bulb-like water-sacs, which are connected with the tube- 
feet on the outside of the ray. " By a contraction of the deli- 
cate muscles in the walls of the ampullae the fluid in the cavity 
is compressed, thereby forcing the tube-feet out. By the con- 
traction of muscles in the tube-feet they are again shortened, 
while the small disk-like terminal sucker clings to some firm 
object. In this way the animal pulls itself along by successive 
steps." By the aid of these ambulacral or tube-feet the starfish 
is able to turn over if placed upon its back. They also act as 
suckers to fasten the starfish to the rocks. When once this is 
accomplished, arm after arm may be broken off before the 
animal can be pulled loose or the feet will relax their hold. 

So-called blood canals accompany the ring and radial canals, 
and associated with them are sometimes two intestinal blood- 
vessels.^ 

Nervous System.^ — " There is a nerve ring and radial nerve, 
frequently in the ectoderm, to which may be added an entero- 
coelic or apical nervous system, possibly of peritoneal origin." 

The circulating fluid is somewhat lymph-like and the circula- 
tion slow. 

" Respiratory organs are represented by the hranchice, or thin- 
walled outpushings of the coelom, either around the mouth, as in 
the Echinoi'dea, or on the aboral surface, as in the Asteroi'dea, 
the hursce of the Ophiuroi'dea, the branchial trees of the Holothu- 
roi'dea, and the various parts of the ambulacral system."- 

The alimentary tube is complete, that is, shut off from the 
body cavity and runs through the body. Its length depends upon 
the food of the echinoderm. In carnivorous forms, as the star- 
fish, it is short, but in vegetable feeders, as the sea-urchins 
and sea-cucum^bers, the alimentary tube is two or three times 
the length of the body. 

Multiplication is sexual, as a rule, the sexes being separate 
except in rare cases. Fertilization takes place in the water. 
They never form colonies by budding. 

The metamorphosis, or change from the larval to the adult 
form, is as marked as that from the caterpillar to the butterfly. 

1 Hertwig's " Manual of Zoology," Kingsley, p. 331. 

2 Ibid. 



54 BRANCH ECHINODERMATA 

The larva is bilateral/ while the adult is radial, the development 
being complex. 

Generally the young shift for themselves, but cases are 
recorded of broods being cared for by the female cchinoderm 
in a pouch on the dorsal surface. ■ 

CLASS I. ASTEROIDEA 

To this class belong the starfishes, with their central disks 
and varying number of rays, five being the typical number. 
They live along rocky seacoasts. Fresh water kills them. 
The common starfish {Aste'rias vulga'ris) is abundant along the 
Atlantic coast, especially in the vicinity of oyster-beds, to 
which they do much injury by devouring the oysters. Star- 
fishes are found also on the Pacific coast from Sitka to southern 
California. They are said to devour small fishes as. well as 
crabs. 

The body wall is composed of a thick leathery substance in 
which is embedded a great number of calcareous ossicles 
(12,000 by estimation), many of which are armed with spines 
for protection. Between the spines on the aboral surface are 
soft stalked projections ending in pinchers, called pedicella'rice, 
with which it cleanses the surface of the body and protects 
itself from parasites. 

The alimentary tube extends from the oral to the aboral 
surface. It consists of a mouth, a short esophagus, and a large 
sac-like stomach, which is five lobed and fills most of the disk. 
(See Fig. 41, p. 52.) The stomach is eversible and is furnished 
with muscles for withdrawing it. From the pyloric, or upper, 
division of the stomach the c(Bca extend, a pair into each arm. 
These caeca secrete much fluid, which is emptied into the 
pyloric portion of the stomach and used in digesting the food. 
From the stomach a short conical intestine extends upward 
to the aboral surface. The aboral opening from the intestine is 
not exactly in the center of the disk and is often difficult to find. 
In a few forms it is wholly obliterated. 

Locomotion. — The arms are somewhat flexible, and, aided by 
their tube-feet,^ enable the starfishes to move slowly along in 

1 Hertwig's "Manual of Zoology," Kingsley, p. 331. 

2 See text, Water-vascular System of Echinoderms, p. 52. 



ASTEROIDEA 



55 



search of food. The starfish, by clinging with its sucking disks, 
can travel along horizontal or vertical walls It can bend its 
arms or even its central disk, when necessary, to pass through 
openings or crevices between rocks. As it moves so slowly, its 
direct dispersal is very limited, but since it is not attached, it is 
indirectly distributed by the tides and currents. The exceed- 
ingly minute young are often borne great distances in this way. 
Foods and Feeding. — The starfish is carnivorous and very 
voracious; indeed, it seems to eat continuously. It feeds upon 
barnacles, clams, oysters (Fig. 42), and, it is said, even small 
fishes, or, failing of these, it will eat the garbage thrown along the 
shore, thus acting as a sort of scavenger. The worst damage it 




Fig. 42. — Starfish attacking oysters. (From Fifth Report of Connecticut 
Bureau of Labor Statistics.) 

does by its gluttony is to the oyster-beds. Oysters and clams 
close their shells to the starfish, but it keeps up a steady pull un- 
til it gets them open, when it reaches its arms about its prey and 
extrudes the lower part of its stomach, envelops the soft parts, 
pours out the digestive fluids about them and absorbs them, 
then withdraws its stomach, leaving the indigestible parts of its 
victim outside the body. Further digestion of the absorbed food 
takes place in the pyloric portion of the stomach, aided by the 
secretions of the hepatic caeca. The fact that all indigestible 
parts are '"' rejected " may account for the shortness of the in- 
testine, and certainly does account for the small or lacking anal 
aperture, since there is little left to be '' ejected." 



56 BRANCH ECHINODERMATA 

The nervous system consists of a circumoral nerve ring^ 
from which a nerve proceeds along the ambulacral groove of 
each arm to its tip, where it ends in a so-called " eye-spot " 
which has been proved sensitive to light. 

Special Senses. — Besides the general sense of touch and the 
" eye-spots," already mentioned, there is at the distal end of 
each ray a tentacle-like organ which is supposed to be the organ 
of smell. 

Multiplication is sexual. Fertilization takes place in the 
water. The starfish may reproduce asexually, for if a ray be 
broken off,^ either accidentally or purposely by the animal 
itself, it has the power of reproducing a new disk as well as the 
rest of the arms, with their internal organs. Similarly, if all 
the arms are torn off, the disk has the power of growing out new 
ones. The young are bilaterally symmetric, free-swimming 
animals. The metamorphosis is complicated, resulting finally 
in the radial plan of structure of the adult. 

The starfish, Linckia linckia, is a host for a parasitic gastero- 
pod (Thyca). Some starfishes are gregarious. 

In size they vary from less than 1 inch to 3 feet in diameter. 
In color they may be yellow, brown, red, or purple. 

Geologic Distribution. — The starfishes appeared before the 
close of the Cambrian Period, and have been represented in 
every age up to the present. 

CLASS II. OPHIUROIDEA 

These echinoderms resemble the starfish. The arms are 
slender, jointed, muscular, and are used for locomotion (Fig. 
43). The arms may be much branched, as in the basket-fish, 
and are not hollow as they are in the starfish. The ambulacral 
groove is closed, the tube-feet are on the sides of the arms, 
and have no suckers at their distal ends. 

The arms are much more slender and more flexible than those 
of the starfish, and locomotion, which is faster than that of the 
starfish, is accomplished by the lateral movements of the arms, 
Some species have the power of throwing off pieces of their 
arms when disturbed. 

The digestive organs are confined to the disk, the hepatic 
1 Parker and Haswell, p. 400. 



OPHIUROIDEA 



57 



cseca are absent, and the anal opening is lacking. The madre- 
poric plate is on the oral side. 

Food. — They are carnivorous, feeding upon worms, crabs, and 
shell-fish. They are also scavengers. 

Multiplication. — Some lay their eggs in the water, where they 
are fertilized and develop into a pluteus stage like that of the 




Fig. 43. — Gorgonocep¥alus agrassi^'u (one-fourth natural size). Oral view. 
(Clark, in Bulletin 550, U. S. F. C, 1902.) 

Echinoidea, while others are viviparous and care for their 
broods. In many species there is also a kind of asexual repro- 
duction, the animal dividing through the disk and each half 
regenerating its " other half." 

There are several hundred species known. These echino- 
derms are variously called brittle-stars, serpent-stars, and sand- 



58 



BRANCH ECHINODERMATA 



stars. The one most common on our shores (Ophiopholis) is 
of a " general red hue spotted with brown and paler red." 

CLASS III. ECHINOIDEA 

The globular or disk-hke sea-urchins have the pentameral 
plan, as a cleaned " test " or shell (Fig. 44) will show. 

The body wall is composed of several hundred pentagonal 
calcareous plates arranged in regular order in twenty rows, 
the whole forming a sort of thin case or shell (see Fig. 44). 




Fig. 44. — Sea-urchin (EchVnus micron^ to ina) with spines nearly all removed 
from " test." (Chapin and Rettger.) 

The ossicles, or plates, are armed with very long sharp spines 
for defense (Fig. 45). Alternate rows of plates are perforated 
for the passage of the tube-feet, there being no grooves. These 
ten rows of perforated plates constitute the ambulacral areas, 
and the ten rows of unperf orated plates constitute the inter- 
ambulacral areas. 

Color. — The colors are brown, olive, purple, red, green, or blue. 

The protective resemblance is good. 

The ambulacral system of the sea-urchin is similar in plan 



ECHINOIDEA 



59 



to that of the starfish. Locomotion is very slow and is per- 
formed by the tube-feet, aided by the long spines. 

The pedicellariae are similar to those of the starfish, but are 
more fully developed, having three pinchers instead of two. 

The food consists largely of green algce and brown seaweed, 
for the sea-urchin is a vegetable feeder, though it eats small 
marine animals also. 

Digestive System. — There are five hard white teeth with 
which they gnaw their food. These teeth are connected with a 




Fig. 45. — Strongylocentrotus drobachiensis. Oral view, showing spines, 
" feet," and teeth. (Clark, in Bulletin 550, U. S. F. C, 1902.) 

complicated calcareous framework under muscular control. 
The whole apparatus is called " Aristotle's lantern." 

The intestines are long, coiling about two and a half to three 
times, instead of being short like those of the carnivorous star- 
fish. 

The hepatic caeca and gastric pouches are absent. This 
lack, as well as the structure of the mouth parts and the long 
coiled intestine, correlates with the feeding habits of these 
herbivorous animals. 



60 BRANCH ECHINODERMATA 

The nervous system is upon the same plan as that of the 
starfish. 

Multiplication. — The eggs are laid in the water and fertilized 
by the tadpole-like sperm cells. Some forms have a marsu- 
pium, or brood-pouch, in which the eggs are hatched. 
• Development. — After fertilization, segmentation of the egg 
takes place until the bilaterally symmetric young " pluteus," 
which is very unlike the adult, appears. It is free swimming 
and lives on minute organisms it can procure in the water. As 
it develops it takes on the radiate or pentameral plan of its 
branch. The " sand dollars " so common on both the Pacific 
and the Atlantic coasts are flat sea-urchins with short spines. 

Geologic Distribution. — A primitive type of sea-urchin ap- 
peared in the Ordovician period.^ 

CLASS IV. HOLOTHUROIDEA 

Holothurians are free, and a close examination reveals the 
pentameral plan of the branch, although they are more or less 
bilaterally symmetric. 




Fig. 46. — Cucwma'ria frondo'sa, side view. Note tentacles and rows of 
feet. (Clark, in Bulletin 550, U. S. F. C, 1902.) 

The shape (Fig. 46) is much like that of the garden cucumber 
in our common varieties, but some are long and slender and 
1 Scott's "Geology," p. 381. 



HOLOTHUROIDEA 



61 



qU 



more worm-like in appearance. Some are so long and slender 
that they are sometimes thought to be worms. 

The size varies from \ inch in one species found upon the 
Massachusetts coast, to 3 feet, in another species found in 
Monterey Bay, California. 

The body wall is tough, leathery, muscular, and not so rigid 
as in the starfish or sea-urchin, although minute calcareous 
spicules are scattered throughout it. 

The tube-feet may be in rows, or scattered, or entirely want- 
ing, depending upon the species, of which several hundred are 
recorded. The sea-cucumbers 
move with their long axis parallel 
to the ground. They creep along 
with the help of the tentacles. 

Protective Resemblance^ — 
Their colors, which are reddish 
brown or yellowish, harmonize 
so closely with those of their en- 
vironment that their protective 
resemblance is almost perfect. 
As the animals rest on the bot- 
tom of the sea with their feathery 
tentacles spread out they closely 
resemble the vegetation of the 
sea bottom. A person may 
stand within a foot of the sea- 
cucumber and not see it. 

The alimentary tube (Fig. 47) 
is several times the length of 
the animal, and the intestine is 
coiled in a uniform manner. 

The food of the holothurians consists of organic matter 
obtained from the sand which they swallow, or of small animals 
which they capture with their tentacles. They are nocturnal 
in their feeding habits, resting quietly during the day on the 
bottom of the sea or buried in the sand. 

The respiratory system consists, probably, of the so-called 
" respiratory trees," two hollow, much-branched organs open- 
ing into the cloaca, which is periodically filled with water. 




Fig. 47. — Sea-cucumber ( HoIo- 
thurian) dissected to show ali- 
mentary tube, al.t. (Leuckart.) 



62 BRANCH ECHINODERMATA 

They are probably excretory organs also, and are connected 
with the manipulations of the tentacles.^ 

Multiplication is generally similar to that of the starfish, 
except in rare cases of hermaphroditism. There are also cases 
recorded of the female caring for her brood in dorsal pouches. 
In unfavorable conditions they void the whole viscera and yet 
live and replace the lost parts. '^ 

In the development from the bilateral larva to the radial 
adult there is a marked metamorphosis. 

Several species are hosts for certain parasites. A small 
fish infests the cloaca and branchial trees of one or two species. 
A snail lives in one species and a mussel in another. 

Use. — They are used for food by the Malays, who call them 
" trepang," and use them principally for soups. Millions of 
them are captured in the south seas, where hundreds of vessels 
are engaged in the trepang fisheries. 

Distribution. — Holothurians are widely distributed, being 
found from the arctic to the tropical regions. 

Geologically, they date from the Carboniferous Period. 

CLASS V. CRINOI^DEA 

Crinoids are fixed echinoderms with a flexible stem or stalk 
of calcareous perfora.ted disks, bearing a flower-like body at 
the top of the stem (Fig. 48). This body consists of a cup- 
shaped center bearing' five or ten arms, usually branched. 
The " feather stars," found at a less depth, later become de- 
tached and float around in the water. 

Ambulacral Grooves. — Five ciliated ambulacral grooves 
(Fig. 49) extend from the mouth out on the arms and their 
branches, and give off branches to the pinnules. They serve 
as channels through which the food passes to the mouth, and also 
for the purpose of respiration. 

Food.- — They feed on small crab-like animals and on marine 
unicellular animals and plants. 

The nervous system consists of a nerve ring surrounding the 
mouth, and given off from this nerve ring are a series of ambu- 
lacral nerves which extend the entire length of the arms and 
pinnules. 

1 Parker and Haswell's "Zoology," vol. i, p. 372. ^ ibj^.^ p. 400. 



CRINOIDEA 



63 




Fig. 48. — Crinoid (Pentac^rinus), half natural size. (Brehm.) 




Fig. 49. — Mouth area of a crinoid (Comat^ula), showing the course of the 
intestine leading from the mouth (m) to the vent (a); g, grooves leading 
from arms to mouth. (From Kingsley's " Comparative Zoology," Henry 
Holt and Co., Publishers.) 

Digestive System. — The mouth is directed upward and leads 
into the digestive tract, consisting of esophagus, stomach, and 



64 BKANCH ECHINODERMATA 

intestines. The interradial anal opening (see Fig. 49) is 
situated near the mouth. 

Multiplication. — Crinoids multiply by eggs, which pass 
through complex changes before reaching the adult stage. 

Habitat. — The living crinoids are deep sea animals with 
the exception of two genera, which live at a less depth. Some 
have been dredged from a depth of 11,100 feet. At this depth 
the water pressure must be enormous. 

Geologic Distribution. — Primitive types (the cystids and 
blastoids) of this group are among the most ancient fossils. 
True crinoids appeared before the close of the Cambrian 
Period. They reached their culmination in the Carboniferous 
Period. The crinoid fossils of this period are so numerous that 
many beds of limestone are composed principally of them. 
Burlington, Iowa, and Crawfordsville, Indiana, are noted for 
their numerous and well-preserved fossil crinoids. Crinoids, 
though formerly of such vast numbers, are now almost extinct. 

Important Biologic Facts. — Echinoderms are radially sym- 
metric, but embryology shows that they have developed from 
the bilateral type. It is reasonable to regard those classes of 
echinoderms as the more ancient which have the radial sym- 
metry less completely developed.^ 

The locomotor-ambulacral system is found in no other 
branch. 

The echinoderms are a singularly isolated group, and we 
look in vain among the known members, living and fossils, of 
other branches for any really close allies. 

Classification. — 





Class. 


Examples. 


I. 


Asteroi'dea. 


Starfishes. 


II. 


Ophiuroi'dea. 


" Brittle-stars." 


III. 


Echinoi'dea. 


Sea-urchins. 


IV. 


Holothuroi'dea. 


Sea-cucumbers. 


V. 


Crinoi'dea. 


Sea Lilies, " Feather-stars." 


VI. 


Cystoi'dea. 


Fossil. 


VII. 


Blastoi'dea. 


Paleozoic fossil, as in Class VI. 



1 Parker and Haswell's "Zoology," vol. i, p. 401. 



BRANCH ANNULATA 

The branch Annula'ta is distinguished from the other branches 
of worms by having external and internal segmentation, that is, 
being divided into rmgs or segments (metameres) " containing 
homologous organs or similar portions of a continuous organ."i 
_ They have, usually, a well-developed coelom or body cavity, 
divided into segments by muscular partitions or septa. 

These worms are bilaterally symmetric. The body is usually 
elongated. 

CLASS I. CH^TOPODA 

Class Chaetop'oda consists of fresh-water and marine annelids 
which bear sets, or bristles. The setae arise from special fol- 
licles, and may occur singly or in bunches. These setae, which 
are controlled by special muscles, act as tiny levers in locomo- 
tion. 

They have a body cavity which is partially divided into com- 
partments corresponding to the segments. The alimentary 
tube extends through the body and is usually constricted at the 
septa. There is usually a well-developed circulatory system. 
Respiration is usually through gills or branchiae and through 
the body wall. In some forms the sexes are distinct, while 
other forms are hermaphroditic. Fresh-water annelids de- 
velop without a metamorphosis, but in many marine forms the 
trochosphere larvae occur. 

Few are true parasites, but a number are commensal, habitu- 
ally associating with other animals for their food and shelter. 
Many sea- worms are phosphorescent. 

The earthworm (Lum'bricus) has an elongated cylindric body 
of many segments or metameres. 

Digestive System (Fig. 50).— The mouth is covered by a 
rounded, lobe-like projection, the prostomium. The mouth 
leads mto a small buccal cavity, back of which is the larger, 
thick-walled, muscular pharynx. This pharynx can be pro- 

1 Galloway's " Zoology," 
5 



65 



66 



BRANCH ANNULATA 




al. t. 



truded and retracted. The radially arranged muscular fibers 
which run from the pharynx to the 
body wall retract the pharynx and at 
the same time dilate it. Back of the 
pharynx is the narrow esophagus, with 
a pair of pouches and two pairs of 
calciferous glands, which communicate 
with these pouches and which contain 
a limy fluid. Posterior to the pharynx 
is the thin-walled crop, and back of 
this is the very thick-walled rounded 
gizzard, with its tough, chitinous lin- 
ing, in which the food is ground by 
sand, and from which the intestine ex- 
tends to the anal opening in the pos- 
terior segment. 

The typhlosole, a prominent ridge 
extending along the middle of the dor- 
sal surface of the intestine and dipping 
down into the interior, renders the 
hollow of the intestine crescent shaped. 
This typhlosole increases the absorb- 
ing surface and is well supplied with 
blood-vessels. 

The circulation is carrried on in a 
well-developed system of blood-vessels. 
The dorsal tube extends along the 
median line of the dorsal surface and 
is plainly seen in the live earthworm. 
The forward movement of the blood can 
usually be seen . The ventral blood-ves- 
sel lies below the alimentary tube. In 
this ventral blood-vessel the blood is pro- 
pelled backward by the peristaltic action 
of the tube. The three smaller blood- 
tubes, the subnural and two lateral 
nural tubes, lie close to the nerve cord. 
Each segment has a transverse vessel connecting the dorsal 
and ventral blood-vessels. Those from the sixth to the eleventh 




Fig. 50. — Earthworm 
dissected to show aUment- 
ary tube, al. t. (Froni 
Jordan and Kellogg, 
" Animal Life," D. Apple- 
ton and Co., Publishers.) 



CH^TOPODA 67 

segment are dilated and pulsate ryhthmically, hence are some- 
times called hearts. The blood is red, the color being due to 
the presence of hemoglobin (the same substance which makes 
our blood red) in the liquid itself, though the blood contains 
colorless corpuscles. 

The nervous system consists of a double cerebral ganglion 
connected with a double ventral chain of ganglia by a pair of 
commissures which pass around the esophagus. 

The earthworm has no eyes, yet it can distinguish not only 
light, but the direction from which it comes, and it will crawl 
" away from the light of high intensity and toward a light of low 
intensity." This tendency, and the fact that the moisture of 
the skin would be rapidly evaporated in daytime, and the ab- 
sence of enemies, induce the earthworms to feed at night. 

The earthworm has no organs of hearing, but its general sense 
of touch is so delicate that it detects the approach of danger 
by the jarring of the earth about its burrow. 

It can distinguish and choose between different kinds of food, 
so it must have a sense akin to smell or taste. It is thought that 
the " goblet-shaped bodies " on the prostomium and on the 
anterior segments are the seat of this sense. 

The body wall is composed of, first (on the outside), the cuticle, 
then the epidermis, the dermis, a muscular layer of circular 
fibers, a layer of longitudinal muscle-fibers, and underneath this 
the coelomic epithelium which lines the body cavity. 

Respiration takes place through the thin moist skin which 
is everywhere underlaid by a network of blood-vessels. These 
absorb the oxygen from the air and give off the carbonic acid 
gas through the skin. 

Locomotion. — Each segment, except the one at each end of the 
worm, is furnished with four pairs of setse, or short, stiff, chitin- 
ous bristles. They arise from the setigerous glands or sacs 
made by the infolcUng of the cuticle. By special muscles, at- 
tached to the base of each of these sacs, the setae can be turned 
in different directions. In locomotion the earthworm uses 
these setse as levers. When it moves forward the setse are 
turned backward and stuck into the soil, the longitudinal 
muscles contract, pulling the body together, then the circular 
muscles contract, making the body smaller and longer and fore- 



68 BRANCH ANNULATA 

ing it forward, since the setae prevent its moving backward. 
When the earthworm moves backward the setse are directed 
forward, and the same processes propel the worm backward. 

Excretion. — In all the segments of the body except the first 
three and the posterior one is a pair of tubular kidneys {nephri- 
dia). Each begins in a ciliated funnel — which opens into and 
takes up the waste from the body cavity — in the back part of a 
segment, and continues in a long, much-looped tube, which 
opens externally by a small excretory pore on the ventral 
surface of the segment posterior to the one in which the funnel- 
shaped beginning is situated. 

Multiplication. — The earthworm is hermaphroditic, but 
cross-fertilization takes place. The lateral and dorsal portions 
of the segments from the thirty-second to the thirty-seventh 
are swollen and somewhat fused together, forming a sort of 
girdle (the clitellum). The glands of this clitellum secrete a 
viscid fluid. This secretion hardens, upon exposure to the air, 
and forms a band or collar about the clitellum. This collar 
moves forward, gathers the eggs and sperms^ as it passes the 
openings, and finally is slipped off over the head.^ The ends of 
the collar now close and it forms a tough egg-capsule. The 
egg-capsules are hidden under stones, boards, or logs, or are 
buried in the earth, especially about barnyards and compost 
heaps. '' The worms are about 1 inch long when hatched."^ 

They hibernate below the frost line in winter. 

Enemies. — The chief enemies are moles and birds. To 
avoid the birds they feed at night or early morning, and some- 
times drag a pebble into the mouth of the burrow, closing it 
after them. 

The marine worms (Pohjche^ta) are dioecious, and the young undergo a 
more or less complete metamorphosis. The larva is a trochosphere ^ Some 
burrow in the sand; some are free swimming; some secrete a mucus which 
hardens and forms tubes; others form tubes by sticking together with 
mucus pieces of shell, sand, mud, or limestone. Most of the tube-building 
species are fixed to some object, but a few carry their tubes about. Many 
of these marine worms live in shallow water, but some have been found 
at a depth of 3000 fathoms. 

1 These have been obtained from another earthworm. 

2 Shipley and MacBride, p. 100. 

3 Colton, "Descriptive Zoology." 
* See Glossary 



HIRUDINEA 69 

The nereis, or sand-worm, which is found on the seashore, has a distinct 
head, bearing eyes and tactile sense organs, such as tentacles and palpi. 
Each segment has a fleshy outgrowth, the parapodium, bearing many bristles. 
" This is the first appearance of true appendages, though they are not 
jointed to the body nor in themselves." 

The sand-worm varies in color in different stages, and the length varies 
from 6 inches to 2 feet. 

It has an eversible pharynx, which, when infolded, conceals two horny 
jaws. These jaws are deeply notched and the ends are incurved. When 
food is taken the pharynx is everted, the jaws thrust forth, and the prey 
seized and swallowed. 

CLASS n. GEPHYR^EA 

Class Gephy/ea is composed of oval or spindle-shaped worms, 
which are unsegmented in the adult form. Setae are entirely 
wanting. The mouth, which is at the anterior end, is either 
surrounded by tentacles or oyer hung by a " proboscis " which 
may be several times the length of the body. 

These worms are widely distributed. They live in both 
deep and shallow water and, " for the most part, either in 
natural rock-fissures or in burrows which they excavate in sand 
or mud or in coral or rock." 

CLASS m. HIRUDIN^EA 

The body of the leech tapers at both ends and is flattened 
dorsoventrally. It is composed of many segments which are 
superficially divided into several rings, so that there are not so 
many true segments as there are surface rings. 

The principal order of this class contains the common fresh- 
water leech familiar to barefoot boys. It is a temporary para- 
site on vertebrates. 

The leech (Fig. 51) has no setae nor appendages, but is pro- 
vided with two suckers. The one on the posterior ventral sur- 
face is used for attachment in locomotion, and the other, which 
surrounds the mouth and is not well developed, is used in suck- 
ing the blood into the large crop. In the pouches of this crop, 
it is said, enough blood can be stored to last a year. A narrow 
stomach and a short intestine follow the pouched crop. The 
coelom is considerably obliterated by a growth of muscle and 
connective tissue, called parenchyma. 

Leeches are hermaphroditic. The eggs are usually laid 
in small packets or cocoons, and these are deposited in moist 



70 



BRANCH ANNULATA 



soil. The eggs are hatched in four or five weeks, but it takes 
them several years to mature. Some leeches are said to live 
twenty years. 

Leeches are widely distributed. Many of them are in- 
habitants of fresh water. Some live in salt water, while others 
live in the forests of many regions, especially those of the 

tropics, where they are the terror .of men 

and beasts. 

One species ( Hiru^do sanguisu^ga) is a parasite 
in the nasal passages of man. Another ( Hcemop^- 
sis vo'rax) hves in the pharynx or trachea of the 
horse, being taken in with water when small. 
Another form (BrancheVlion) is a permanent ex- 
ternal parasite on fishes. 

Distribution. — The members of branch 
Annulata are widely distributed, the rep- 
resentatives of its many species being 
found from frigid to tropical regions, and 
even in the isolated islands of the sea. 

It is known that marine worms existed 
in the Cambrian Period by their " tracks 
and borings in the sand, which are now 
consolidated into hard rocks." 

Economic Importance. — The earth- 
worm swallows the soil which it exca- 
vates for the sake of the partially de- 
cayed organic matter it contains, which 
the worm appropriates to the building 
up of its body tissue. The indigestible 
portions it deposits on the surface at 
night as coiled castings. They also feed 
on fresh or decayed leaves which they 
drag into their burrows, and sometimes 
upon young seedlings and tender roots. 

Darwin, who studied the earthworm for 

forty years, estimated that in the tillable 

soil of England there were fifty thousand 

earthworms to the acre, and that they brought to the surface 

from 10 to 18 tons of soil annually. In this way the whole 



Fig. 51. — Section of 
a leech: a, Anterior 
sucker; b, posterior 
sucker; c, anus; d, d, d, 
stomach; ce, esophagus; 
i, intestine; s, s, glands 
of the skin. (Holder.) 



HIRUDINEA 71 

superficial layer would be enriched by passing through their 
bodies in a few years. Their burrows may extend vertically or 
obliquely for several feet underground, their depth depending 
upon the distance of the moist soil from the surface. " They are 
connected by underground tunnels, so that the soil is thoroughly 
exposed to the chemical action of the gases and acids of the air 
and water."! Thus the action of the earthworm has both a 
chemical and a mechanical effect upon the soil. 

Leeches were formerly used very frequently by doctors when 
bleeding was more often practised. They are still sometimes 
thus used. They are raised in France for commercial purposes. 
Swamps are stocked with them and they are fed upon old and 
worn out farm animals. 

Important Biologic Facts.— This branch is distinguished from 
all preceding groups by its metameric segmentation. The 
excretory system is characterized by the peculiar nephridia. 
There is a well-developed circulatory system and a circulating 
fluid containing hemoglobin. In leeches eyes are found, while 
the "goblet-shaped organs" in leeches and earthworms are 
thought to be the seat of smell or taste. True appendages ap- 
pear in the Nereis. 

The trochosphere larvae show relationship between Chsetopoda 
and the Turbellaria and the Nemertinia. 

Classification. — 

(^Idss. Examples. 

I. Chsetop'oda. Earthworms, Sand- worms. 

II. Gephyr'ea. Sipunculus. 

III. Hirudin'ea. Leeches. 

1 Jackson and Daugherty, "Agriculture Through the Laboratory and 
bchool Garden." 



BRANCH MOLLUS'CA 

These animals have soft, unsegmented bodies, as contrasted 
with the segmented Arthropoda. The body is generally bi- 
laterally symmetric, but it may be asymmetric, as in the snail. 
They vary in size from a fraction of an inch to from 2 to 5 feet 
in length; and in weight from a fraction of an ounce to 500 
pounds. The body may be naked, as the slug; or covered 




Fig. 52. — Part of a bunch of oysters from Great Point Clear Reef, showing 
attachment of barnacles and mussels. (Bulletin, U. S. F. C, 1895.) 



with a univalve shell, as the snail; or with a bivalve shell, 
as in the common mussel; or it may have an internal horny 
pen, as in the squid. The structure and form of the Mollusca 
are very various, and the number of known living and fossil 
species exceeds forty thousand. Some mollusks are marine, 
some are fresh-water forms, and others are terrestrial. 
72 



PELECYPODA 73 

The circulatory system consists of a dorsal heart of one 
ventricle and one or more auricles, enclosed in a pericardium. 
Aortse carry the blood from the ventricle to different parts of the 
body, but the blood-vascular system is not entirely closed. 

Respiration is carried on through the body wah in a few 
Mollusca, but most of them breathe through gills or lungs. 

The nervous system is characterized by three pairs of ganglia 
which are joined by connective nerve cords. The cerebral 
ganglia are situated dorsal to the esophagus and supply the 
tentacles and eyes. The pedal ganglia lie ventral to the mouth 
and supply the foot and otocysts. The visceral ganglia, also 
ventral, but farther back, supply the body, the mantle, and the 
so-called " osphradia," or olfactory organs. Some mollusks 
lack special sense organs. 

Locomotion is accomplished by the single so-called "foot," 
a muscular plowshare-shaped thickening of the body. 

Multiplication. — The Mollusca may be sexually separate or 
hermaphroditic . 

This branch includes some very valuable food animals for man, 
as clams and oysters. Other examples are snails, slugs, scallops, 
cuttle-fishes, squids, and fresh-water mussels. 

CLASS I. PELECYPODA 

This class is called by various names by different zoologists, 
depending upon the character taken for the basis of classifica- 
tion — as Aglossa (without a tongue), Acephala (without a 
head), Bivalva (of two valves), Pelecyp'oda (hatchet-footed), 
Lamellibranchiata (leaf-hke gilled). We may then characterize 
this class as the hatchet-footed, headless, tongueless, bivalved, 
leaf-like gilled mollusks. Mussels, clams, and oysters are com- 
mon examples of this class. 

The body is soft, unsegmented, and is modified into the large 
" foot " used for locomotion. The mantle, a great fold of skin, 
covers the body, one lobe over each side. Between the mantle 
lobes and the body are the four large leaf-like gills. The labial 
palpi are the small leaf-like structures anterior to the gills, and 
lead into the mouth. This organ secretes the shell. 

Food consists of small organisms which the water carries 
into the mantle cavity and to the cihated labial palpi, which 



74 



BRANCH MOLLUSCA 



pass the food into the mouth. From thence the food passes 
into the stomach and to the long coiled intestine which passes 
through the pericardium, usually perforates the ventricle, and 
ends dorsal to the posterior adductor muscle. 

The Pelecypoda are sexual and sometimes hermaphroditic. 
There is a metamorphosis, there being usually a trochosphere 
stage. 

The sea mussel {My'tilus) is an example of this class. Great clusters 
of this edible mussel are found just below low-tide marks. The shell is 
generally of a purple or dark color. The long slender foot (Fig. .53) throws 
out yellowish horny fibers (the byssus), by which the mussel attaches 




Fig. 53. — Mytilus edulis: 0, Mouth; S, labial palps; P, foot; B, byssus 
secretion; Br, gills; M, thickened edge of mantle. (After Glaus.) 



itself to foreign objects. If food becomes scarce or conditions unfavorable, 
it can detach itself and slowly move to another position by stretching out 
the threads of the byssus and attaching them ahead or above, and then 
drawing itself up to them, hence it is sometimes called the " climbing 
mussel." 

Anosmia, of the same order as MyHilus, is permanently fixed. 

The oyster (Os^trea) is a member of this class, which in adult life is fixed 
to the sea bottom or to some foreign object — very often the shell of another 
oyster. Great clumps (see Fig. 52, p. 72) may be thus fastened together, 
but their union is not organic. Oysters vary in size from a few inches to 
2 or 3 feet, the largest being a Japanese species. 

The shell of the oyster (Fig. 54) is rougher than that of the clam, and the 
hinge is at the pointed end, which corresponds to the anterior end of the 
clam. Its two valves are not alike, but the lower or left one is much 
larger and becomes deep enough to contain the body, while the upper or 
right valve is flat and serves as a lid. There is but one adductor muscle. 



PELECYPODA 



75 



By its contraction the shell is closed. Its location is changed from year to 
year as the animal grows. A brown scar in the shell indicates where the 
attachment has been. The oyster can open its shell but little. 

The oyster, since it is fixed, needs no organ of locomotion, and so has no 
foot. Neither has it any siphon, but the food-bearing water (Fig. 55) 
enters along the curved border of the shell and passes out near the larger 





Fig. 54. — Shell of typical American oyster: 1, Inner face; 2, outer face. 
(Report U. S. Geol. Survey.) 

end on the straight side. A fresh supply of sea-water is necessary to fur- 
nish it with food and oxygen. If the oysters settle too deep in the mud 
or if they are covered by silt and sand in time of storms they smother. 

Our species of oysters {Ostrea virginiana) is bisexual, while the European 
species are hermaphroditic. i The reproductive organ is attached to the 

1 "Hertwig's Manual of Zoology," Kinglsey, p. 367. 



76 



BRANCH MOLLUSCA 



large adductor muscle. The eggs are deposited in the water. They 
are very numerous. It has been estimated that one female will produce 
from 9,000,000 to 40,000,000 eggs in a single season. The breeding .seasoii 
is from May to August. If the eggs are not eaten by enemies or carried 
away by currents, they sink to the bottom. After a few hours of develop- 
ment the larvEe swim to the surface. Multitudes of these larvae are de- 
voured by surface-living fishes. The larva; (Fig. 56) swim by means of 
cilia. In a few days the larvae or fry, as they are called, sink to the bottom 




Fig. 55.— Food of South Carolina oyster. A few typical organisms 
(x 225). Numbers 1 to 20 are diatoms. 1-5, Navicula (Bory); 6, N 
didyma (K.); 7, Pinnularia radiosa (?) (K. S.); 8, Amphora sp. (K.) 
9, Pleurosigma fasciola (E. S.); 10, P. littorale (S.); 11, P. strigosum (S.) 
12, Actinocyclus undulatus (K.); 13, Coscinodiscus radiatus (E.); 14, 
Cyclotella rotula (E.); 15, Synedra sp. (E.); 16, Diatoma sp. (De C 
17, Cymbella sp. (Ag.); 18, Mastogloia smithii (Thw.); 19, Triceratium 
alternans (Br. Bai.); 20, Biddulphia sp. (Gr.); 21, Grain of pine pollen 
(Pinus rigida); 22, Foraminifera (Rotalia); 23, Zoospore (Ulva?); 24, 
Spicules. (After Bashford Dean.) (From Moore, U. S. Com. of Fish 
and Fisheries.) 

and attach themselves by the mantle-fold to some other oyster or to any 
object with which they come in contact. It takes them from three to 
five years to attain their growth. The blue crab (see Fig. 74, p. 101) is very 
destructive to the young oyster. 

One of the greatest enemies of the oyster is the starfish (see p. 55). 
Other enemies (Fig. 57) are boring snails, boring sponges, and internal 
parasites. One little crab {Pinnothe'res) which lives in the mantle cavity 
seems to be an example of symbiosis rather than a parasite; at least it does 
not appear to harm the oyster. 



PELECYPODA 



77 




Oysters abound in quiet, shallow inlets of the Atlantic coast south of 
Cape Cod, and of the Gulf of ^lexico. We have the best oysters in the 
world. 1 Our most extensive oyster-beds are on the Chesapeake Bay, at 
Baltimore, where they cover 3000 acres and furnish millions of bushels 
j'early. We not onh' supply the markets of our own great cities, but send 
large quantities to British markets. Oysters are found also on the Pacific 
coast, on the coasts of Europe, of Australia, 
and of Japan. 

The scallop (Pecten) has an almost round, 
fluted shell with a straight hinge without 
teeth, and with unequal valves, one being 
more nearh' flat than the other. The shell is 
usually brilliantly tinted. The foot is rudi- 
mentary or altogether lacking. The mantle- 
folds are fringed with slender tentacles and 
the edge of each lobe is set -n-ith a row of 
brilliant bluish " eyes." When at rest the 
scallop lies on the sea bottom with its one ad- 
ductor muscle relaxed and its shell open. If 
disturbed, it quickly closes the shell by con- 
tracting the strong muscle. This catches a 
quantity of water which is forcibly ejected 
through a round aperture at either end of the 
straight flange of the hinge. The reaction 
caused bj' forcing this water against the great 
body of water outside propels the animal for- 
ward. Thus, by rapidly opening and closing 
its shell, it swims through the water with 
comparative ease. 

The edible scallop {Pec'ten irra'dians) is 
about 21 inches in diameter and its color 
varies from a whitish to a reddish or purple 

hue. The adductor muscle is the portion used by man for food, 
scallop is found on the Atlantic coast south of Cape Cod. 

Pec' ten max'imus, found on the coast of Great Britain, in water 30 to 40 
fathoms deep, is much larger. Its deeper shell was formerly used as a 
baking-dish for oysters, hence the origin of the term " scalloped oysters." 

The shell of another form common in the Meditermaean Sea {Pec'ten 
jacohoe^us) was worn as a badge bj' the crusaders returning from the Holy 
Land. 

The so-called pearl-oyster (Meleagri'na), which does not belong to the 
oyster family at all, has a shell which is more nearly circular, a little convex, 
and sometimes a foot in diameter. They are found in ^Madagascar, 
Panama, Ceylon, East Indies, Australia, South Sea islands, Philippines, 
and the West Indies. 

Pearls are depo.sits of nacre formed about some foreign substance. 
Prof. Jameson has discovered- by investigation upon the sea-mussel that, 
in their case, pearls are caused by a parasitic worm {Trematode). Pearls 
are collected by divers who go down from 6 to 8 fathoms for them. Hun- 

^ "On the coasts of Holland, Belgium, and France far greater care is taken 
of their species (Os'trea ed'uUs) than we take of ours (Os'trea Virginia' na), 
but our natural conditions are superior to theirs. ' ' — LinviUe and Kelly, p. 169. 

2 Linville and Kelly's " General Zoology," p. 173. 



Fig. 56. — Right side of 
embryonic oyster, six days 
old: w, Mouth; s, vent;?, 
right lobe of hver; li, 
velum. (Moore, Bull. U. 
S. F. C, 1897.) 



This 



78 



BRANCH MOLLUSCA 



dreds of vessels are engaged in this industry. Pearls of various shapes are 
found. Their colors may be white, yellow, pink, blue, red, green, or even 




Fig. 57. — Some enemies of the oyster: 1, Drill (Urosalpinx cinerea); 
2, mussel (My^tilus edulis); 3, Sabellaria vulgaris; 4, periwinkle {Fulgur 
carica). (Report of Fish Commision for 1897.) 



black. Round lustrous white ones are most prized in Europe and Americaj 
but those of the yellowish hue are preferred by Asiatics.. 




79 



Fig. 58. — Section of AnodonHa, showing the digestive tube: m, Mouth; 
g, gullet; I, liver; s, stomach; r, i, intestine; o, anus; p, pericardium; k, 
kidney; s.c, chamber above the gills. (Furneaux.) 




vg. 



Fig. 59. — Anodon^ta, lying in one valve, with upper lobe of the mantle 
removed: p, Pericardium; /.-, kidney; p.r., posterior retractor muscle; 
p.a., posterior adductor muscle; a.a., anterior adductor muscle; a.r., anterior 
retractor muscle; p.p., protractor pedis muscle; a, anus; e.s., exhalent 
siphon; i.s., inhalent siphon; l.m., cut edge of the mantle; o.g., outer gill- 
plate; ml., mantle lobe; v.g., inner gill-plate; v, internal organs; /, foot; 
Z.p., labial palps; I, liver; p.l., pallial line. (Furneaux.) 

Fresh-water mussels (Figs. 58, 59) or clams of our ponds, lakes, and 
streams have firm leaf-like gills and two nearly equal adductor muscles. 



80 



BRANCH MOLLUSCA 



The siphon is incomplete and the pallial line is entire, that is, without 
sinus or indentation. The foot is long and compressed. The valves of 
the shell are held together by the strong adductor muscles, and opened, 
when these relax, by the elastic spring or hinge ligament. The shells are 
a dull black on the outside, and pearly white, tinted with iridescent hues, 
on the inside. The shell of the Unio is not so large and strong as that of 
Anodonta, while the latter genus has no hinged teeth. Clams are found 
in ponds and large streams (which do not dry 
up in the summer), distributed along the direction 
of the strongest currents to insure food supply. 
They are partly buried in the mud, the open edge 
of the shell down and the valves slightly apart, 
with the fleshy foot protruding from the anterior 
ventral margin. When disturbed, the foot and 
edges of the mantle-lobes are retracted and the 
valves tightly closed. 

The shell is the mussel's principal means of 
defense. It has many enemies besides man, such 
as the musk-rat, raccoon, mink, otter, and other 
mammals that live in and about the streams 
where the clam is found. Such animals as the 
musk-rat gnaw off the hinge ligament to get the 
shell open. 

The young clams are carried in the gills, and 
were formerly mistaken for parasites, and are 
called glochidea. They differ much in shape from 
the adult. The glochidea, or young clams, pass 
out through the exhalant siphon and attach them- 
selves by hooks on the valves to the gills or fins of 
fishes, by which they are protected from enemies 
and kept supplied with fresh water until suffi- 
ciently mature for independent existence, when 
they detach themselves from their host and drop 
to the bottom of the stream. 

The giant clam {Tridac'na gi'gas) of the tropics 
has a shell from 2 to 4 feet long, which may 
weigh from 300 to 500 pounds. 

The soft-shelled clam {My^a arena' ria) abounds 
in the mud flats of the Atlantic coast north of 
Cape Cod. The young clams swim about on the 
surface of the water. After the shell appears, 
they sink to the bottom and attach themselves by 
the byssus. When the clam is about \ inch long, 
the byssus disappears and the animal buries itself 
in the mud. As it grows, it keeps enlarging and 
deepening its burrow until it may extend from 
8 to 12 inches below the surface of the mud. The long siphons are extended 
up to within reach of the sea-water, whose currents bring to the clam food 
and air. The water enters through the ventral siphon, is driven through 
the gills, and finally passes out through the excretory tube, the dorsal 
siphon. 

Another form much used for food is the " Quahog " {Venus mercenaria), 
which is characteristic of warmer waters, and is found from Cape Cod to 
Texas. It burrows a little way below the surface, but is often found with 



Fig. 60.— Tere'dona- 
vaVis, removed from its 
calcareous tube, with 
elongated siphons. 

(Quatrefages.) 



GASTEROPODA 81 

its shell partly exposed. Along the Atlantic coast people use the Mya 
or Venus for their " clam-bakes." Many hundred bushels are used every 
year for this purpose. 

The razor-shell clams have similar habits. They are concealed in 
vertical holes in the sand with the posterior end of the shell uppermost. 
They have a powerful club-shaped foot, and can dig so rapidly that unless 
one approaches very cautiously they escape from view. They seem to be 
sensitive to hght and to the " jar " made by approaching footsteps. 

The borer {Phobias) has its brittle but very hard shell marked like a file, 
with which it bores into the hardest rocks. The united siphons are longer 
than the rest of the body. Some forms are phosphorescent, emitting 
bluish-white light. , , . 

The ship-worm (Tere^do) (Fig. 60), another borer, works into wood, domg 
much damage to ships m the tropics. The larva enters the wood when it is 
extremely small and enlarges the tunnel as it grows. The wood which 
it excavates is not used for food, but is carried off by the excretory siphon. 
Its food, which consists of microscopic organisms, is brought in by the 
currents. The amount of damage these borers do. seems incredible. They 
completely honeycomb the hull of a wooden vessel. The best protection 
against them is the sheathing of the hull with copper. Paknetto is the 
best resistant among woods. The ship-worms caused the destruction of 
a dam in Holland, threatening destruction to the country. Their dis- 
persal is wide, since they are carried all over the world in the floating wood 
which they attack. 

CLASS II. GASTEROP^ODA 

These are asymmetric, usually univalve mollusks, and the 
head region bears either one or two pairs of tentacles. As in 
the snail (Fig. 61), the eyes are borne either at the bases or at the 




Fig. 61. — A snail. (After Tenney.) 

tips of the tentacles. The shorter tentacles are probably organs 
of smell. The head contains the mouth, in which is the tongue, 
covered by the radula, a ribbon-like organ supplied with 
chitinous teeth and used for rasping the food. 

The mantle is not divided into two parts as in the mussel, but 
unites around the neck, leaving but a small respiratory aperture 
6 



82 



BRANCH MOLLUSCA 



into the mantle cavity. The foot is broad and flat and is used 
for locomotion. Respiration is accomplished through the wall 
of the mantle cavity, or by one or two plume-like gills or 
clenidia in the mantle cavity. In the air-breathing forms there 
may be simply a pulmonary sac. 

The shell is a spiral, either flat or elongated (Fig. 62), and is 
usually closed by a flap or operculum (a horny plate growing 
on the posterior portion of the foot) for protection. 



apex 



suture ■.;•■■-■- 



body whorl 




> whorls forming the sfire 



aperture 



Fig. 62. — ^A snail shell. (Morse.) 



Some Gasteropods are marine, some are fresh-water forms, 
and still others are terrestrial. 



The limpets {PateVlidce) are uncoiled forms with open conical shells. 
They are found adhering to rocks between tide-marks. The foot acts as 
a sucker, enabling the animal to resist a force of a thousand times its weight 
when one attempts to detach it. The common limpet {Patella vulgata) is 
used as food. It feeds upon seaweeds. 

The ear-shells {HaliotHdce) , found on our western coast, have a row of 
perforations near the margin of the shell through which the tentacles 
pass to the exterior. The shells are much used in inlaid work on account 
of their beautiful iridescent color. They are also used as food, and the 
shells are used for making buttons. 

■^ The cowries {CyprceHdoB) have richly enameled shells with small open- 
ings. They are beautiful and are sold for ornaments, some species being 
much prized. A beautiful yellow shell, an inch or less long, which abounds 
in the East Indies, is used as money in Siam and in parts of Africa: 6400 
cowries are equal to about 36 cents. The cowries are tropical, but a few 
species are found in temperate seas. 



GASTEROPODA 83 

The helmet-shells {Cassid'idoe) are composed of layers of different colored 
material and are used for carving cameos. 

The tritons or sea conchs {Triton' idee) have handsome shells, frequently 
more than a foot in length. The shells of one species is used by the South Sea 
Islanders as a trumpet. The TritonHdce have a proboscis, a well-developed 
siphon, and a short foot. 

" The long, nearly cylindric shells of the Cavolinidae make up much of 
the ' pteropod ooze ' of the deep seas." 

The common periwinkle {Littori'na) (see Fig. 57, p. 78) abounds on the 
coast of New England and southward, where it is used as food. It is 
a native of Europe. It is a vegetable feeder, and is valuable in cleaning 
up the seaweeds from oyster-beds. 

The oyster drill ( Urosal/'pinx ciner^ea) (see Fig. 57, p. 78) bores a hole 
through the shell of the oyster and feeds upon its soft parts. 

Natica is another drilling sea-snail common on our Eastern coast. 
It burrows in the sand for clams and bores a hole with its radula, rotating 
its own body in the action. 

The Nudibranchs. — In the Nudibranchs the shell is entirely absent in 
the adult. True ctenidia are replaced as breathing organs by a number of 
secondary branchiae, sometimes simple, sometimes branched processes or 
leaf-like tufts, which may be distributed over the dorsal surface (as in 
E'olis), or placed in a row on each side beneath the mantle-flap (as in 
Pleurophylli^dia). These soft naked sea-slugs live in shallow water near 
the shore, crawling about and feeding upon the seaweeds. Their protect- 
ive resemblance is very great on account of both color and form. They 
move very slowly. This also aids them in escaping the notice of their 
enemies. 

The land snails and slugs {Puhnona'ta) are air breathing. The air 
enters the mantle cavity through a small opening which is near the right 
side in the dextral forms (that is, the spiral of the shell turns like the hands 
of a clock from left to right), and on the left side in the left-handed (sinis- 
tral) forms. 

Land snails ( HelicHdce) are common in moist woods. They come out at 
night or in cloudy weather to feed on succulent vegetation. When they 
are numerous they do much damage. They, in common with the pond 
snails, have thin spiral shells. They have two pairs of tentacles. The 
upper and larger pair bears the eyes at their tips, and the shorter pair is the 
organ of touch. (See Fig. 61, p. 81.) 

The land snail ( Helix) has no operculum, and when frost comes it with- 
draws into its shell, fitting the opening to some smooth object, and secretes 
a layer of mucus. This hardens upon drying and forms a tough membrane, 
the epiphragm, which closes the opening. In at least one species of Helix 
a small hole is found just below the lung aperture, through which an ex- 
change of gases may take place. 

As a rule, snails lay their eggs in strings or masses, but the land snails 
bury their eggs singly or deposit them thus in m>oist places. Snails are 
used as food, being even shipped to the United States from Europe. 

Land slugs- {Limac'idce) are naked. The shell is vestigial and con- 
cealed by the mantle. T^ey have a rasping tongue like the snail's. The 
giant yellow slug of California {Ari'olimax californica) reaches a length of 
12 inches. 

The Pulmonata are hermaphroditic. The garden snail hibernates by 
coihng up in its underground burrow in winter. 

Pond Snails. — The common pond snails have but one pair of tentacles, 
and the eyes are situated at the bases of these. They breathe by means 



84 BRANCH MOLLUSCA 

of a lung-sac instead of by gills, and must come to the surface occasionally 
for air. In genus Physa the spiral of the shell is left-handed; in Limnce^a, 
right-handed, and in Planor^bis the shell is discoid or a flat spiral. 

The eggs of genus Physa are deposited in gelatinous, transparent, 
oblong capsules of an inch or less in length attached to submerged sticks 
or leaves. Genus Limnce^a lays the eggs late in spring in capsules sur- 
rounded by a mass of jelly. The young pass through a metamorphosis. 

Still other pond or river snails breathe by means of gills. They live in 
the bottom of ponds or streams and are carnivorous. 

CLASS III. CEPHALOPODA 

Class Cephalop'oda (head-footed) consists of such forms as the 
squid, cuttle-fish, octopus, and nautilus. They are all marine, 
and, in many respects, the most highly developed of all mollusks. 
There is a distinct head, bearing a pair of large well-developed 
eyes, and surrounded by arms or tentacles which are modifica- 
tions of the anterior margins of the foot.^ The posterior part of 
the foot is transformed into a funnel-like siphon. 

The body is bilaterally symmetric. Respiration is through 
gills which line the mantle cavity. The shell may be external, 
as in the nautilus; or internal, as the pen of the squid; or lacking, 
as in the octopus. 

They are usually carnivorous. Some are solitary, as the 
devil-fish; others, as the squid, go in immense shoals. The 
senior author has seen acres of ground covered with the 
catches of them on the Pacific coast. 

The circulatory system is closed and consists of a somewhat 
complete heart and arteries, capillaries and veins. 

The principal ganglia are grouped about the esophagus. 
The nervous system is the most highly developed of any of the 
branch, consequently they are the most intelligent of all mol- 
lusks. 

They have the power of quickly changing color to harmonize 
with their environment. 

Cuttlefishes are rapid-swimming Cephalopoda living at a depth of several 
fathoms, but sometimes coming into shallower water. The cuttlefish has a 
distinct head bearing ten long arms, and a pair of highly developed eyes 
resembling those of a fish. The free end of the head bears the mouth. 
The inner surface of each arm or tentacle is flat and bears four longitudinal 
rows of suckers. The fourth pair of tentacles is much longer and more 
slender than the others, and the club-shaped end bears suckers. The 

1 See McMurrich, p. 341. 



CEPHALOPODA 



85 



body is covered by the thick integument of the mantle. The internal 
shell is calcareous and furnishes the cuttlebone used for canary birds. 

Cuttlefishes are carnivorous, feeding upon crabs, clams, or fishes. 
They delight in the daylight and in the open sea, so they need to be pro- 
tected from the view of their enemies. For this purpose they discharge 
an inky fluid to cloud the water so as to escape detection. The dark- 
colored secretion is carried in the ink-bag connected with the siphon. 
The ink was used in ancient times as a writing fluid. The sepia ink used 
by artists in making the sepia pictures is manufactured from this fluid of the 
cuttlefish. The cuttlefish is also used as an article of food in the Old 
World. 




Fig. 63. — Loli'go vulga'ris. (After Verany.) 

Squids (Fig. 63) swim in schools. They, unlike cuttlefishes, are noc- 
turnal. They are carnivorous, feeding upon young fishes. The common 
squid is a foot or less in length. The internal shell is a horny " pen " 
shaped something like a feather, which is embedded in the dorsal portion 
of the mantle. By alternately taking water into the mantle cavity and 
forcing it out, the squid is driven rapidly backward. It avoids detection 
by its color changes and by an inky discharge like that of the cuttlefishes. 
It feeds upon small fishes and crabs, which it kills by biting with its power- 
ful horny beak. Its enemies are large fishes and man. Giant squids are 
over 9 feet long, with arms 20 or 30 feet in length. 

The octopus is another member of this class. It has a short subspherical 
body without any shell. It has eight sucker-bearing arms, with which it 



86 



BRANCH MOLLUSCA 




Fig. 64. — The chambered nautilus. 

"Year after year beheld the silent toil 

That spread his lustrous coil; ' 

Still, as the spiral grew, 
He left the past year's dwelling for the new, 
Stole with soft step its shining archway through, 

Built up its idle door, 
Stretched in his last-found home, and knew the old no more. 

"Thanks for the heavenly message brought by thee. 

Child of the wandering sea. 

Cast from her lap, forlorn! 
From thy dead lips a clearer note is born 
Than ever Triton blew from wreathed horn! 

While on mine ear it rings. 
Through the deep caves of thought I hear a voice that sings:— 



Build thee more stately mansions, O my soul. 

As the swift seasons roll! 

Leave thy low- vaulted past! 
Let each new temple, nobler than the last, 
Shut thee from heaven with a dome more vast, 

Till thou at length art free. 
Leaving thine outgrown shell by life's unresting sea." 

Oliver Wendell Holmes. 



CEPHALOPODA 87 

grasps its prey. " Devil-fishes " are found in all seas. They are gregarious 
when young, but the adult is solitary. They creep about among the rocks 
upon the extremities of their arms, generally moving sideways; or swim 
rapidly, either forward or backward. The arms are somewhat webbed at 
the bases. 

Some devil-fishes measure 12 to 15 feet, others but a few inches. They 
are found on our western coast and in the Pacific islands. They are much 
used for food along the Mediterranean Sea and by the Chinese and Italians 
of San Francisco. 

The Nautilus (Fig. 64). — This Cephalopod has a many-chambered, 
spiral, univalved shell, lined with pearly nacre, hence is often called the 
"pearly nautilus." It has four gills instead of two. It crawls about 
on the sea bottom by means of its many (about forty) small tentacles. 
It has no suckers. The outer chamber of the shell is a large compartment 
in which the animal lives. As it grows, the nautilus partitions off the space 
behind it and moves forward. A calcareous tube containing the siphimcle, 
a slender tubular continuation of the body, extends through all the septa. 
The abandoned compartments are filled with air. 

The nautilus has a beak and a rasping tongue, like those of the squid. 
Each of its two disk-shaped eyes is attached by its convex side to a short 
thick stalk. The aperture of the eye is small, and there is no cornea, no 
iris, nor vitreous humor, but simply the retina at the base of a disk or pit. 
The nautilus has not the power of changing its color, and has no ink sac. 

It lives in the deep water in the south Pacific Ocean, and has been but 
little studied. Many of the species of former ages are extinct. This is the 
" chambered nautilus," immortalized by Oliver Wendell Holmes. 

Economic Importance. — MoUusks are probably of more 
direct use to man than any other invertebrate branch. The 
oyster industry is of vast importance, giving employment to 
thousands of persons and bringing an annual income of millions 
of dollars. Clams are also used extensively for food, and peri- 
winkles and snails less extensively. We get also pearls, and 
the mother-of-pearl for the making of buttons, knife-handles, 
and novelties. Factories have been established in Illinois and 
Iowa for making buttons on a large scale from the fresh-water 
mussel shell. This industry threatens to exterminate these 
bivalves unless means are taken to protect and perpetuate them. 

The squid is extensively used as bait in cod-fishing, while 
both the squid and the cuttlefish furnish the sepia ink used by 
artists. The cuttlebone used for canaries is another product 
of the cuttlefishes. 

The ship-worm does much harm to dikes, wharves, and piles, 
or any wooden structures which have been in water some time. 

Important Biologic Facts. — The mollusks are the most highly 
organized of any of the invertebrates except the Arthropoda, 



88 BRANCH MOLLUSCA 

and many zoologists place them above the Arthropoda. They 
have a well-defined circulatory system and nervous system and 
especially highly developed eyes. They usually have a metamor- 
phosis, some of the stages of which show indications of affinity 
with "worms." 
Classification. — 

Class. Examples. 

Pel'ecyp'oda. Sea-mussel, Oysters, Scallop, 

Fresh- water mussel. 
Gas'terop'oda. Limpets, Periwinkle, Snails. 

Ceph'alop'oda. Cuttlefish, Octopus, Nautilus. 



BRANCH ARTHROPODA 

Akthrop'oda may be characterized as animals having bi- 
laterally symmetric segmented bodies with jointed appendages 
and a chitinous exoskeleton. The segments of the body are 
not so numerous as in the worms. 

This branch includes a vast assemblage of animals which 
are widely distributed over the earth. They vary in habitat, 
being aquatic, terrestrial, subterranean, aerial, or some com- 
bination of these. 

Some are of direct use in furnishing food for man, as the 
lobster and the bee. Many cross-fertilize plants, and are thus 
of indirect use to man. As common examples of this branch 
may be named the lobsters, crabs, crayfishes, spiders, " thou- 
sand-legs," and insects. 

The digestive system is between the circulatory system and 
the nervous system. It is not much coiled, but runs almost 
straight through the body. (See Fig. 69.) 

The circulatory system consists of a dorsal blood-vessel 
open at the anterior end. The blood is pumped forward. It 
fills all the irregular spaces of the body, through which it bathes 
all the tissues and makes its way back to the dorsal vessel. 
The corpuscles are colorless and ameboid. 

The respiratory system consists of gills in the aquatic forms, 
and of air-tubes or tracheae in the insects and other terres- 
trial forms. 

The nervous system consists generally of a double chain of 
ganglia, connected by a double nerve cord, running along the 
ventral side of the body. (See Fig. 69, N.) We should expect 
to find a pair of ganglia to each segment, but several ganglia may 
be united, as in the crayfish, where there are thirteen well-marked 
ganglia, the three anterior ones uniting to form the so-called 
brain. 

Multiplication. — The sexes are usually distinct. Multiplica- 
tion is generally by fertilized eggs. 

89 



90 BRANCH ARTHROPODA 



CLASS I. CRUSTA'CEA 

As examples of this class may be named crayfishes, lobsters, 
crabs, and " pill-bugs." The body has a limited number of 
segments, about twenty in the crayfish. Each pair of append- 
ages is regarded as being attached to a different segment. 
The head and thorax are united and called cephalothorax. 
The chitinous covering, rendered hard by deposits of carbonate 
and phosphate of lime, is called the carapace. 

Respiration is by gills, or branchiae, though some breathe 
through the skin. 

The appendages are biramous, as seen in the swimmerets of 
the crayfish. A typically developed appendage, as the third 
pair of swimmerets, consists of a main stalk (protopod) and two 
branches, the outer (exopod) and the inner (endopod). Several 
of the appendages lack some of these parts. The student should 
homologize the appendages and tell or demonstrate which ones 
have missing parts. 

The class Criista'cea is usually divided into two sub-classes, 
the En'tomos'traca and the MaVacos'traca, with several orders 
under each. 

Sub-class Entomostraca is composed of crustaceans with a 
varying number of joints or segments. They are usually small 
or microscopic. There is a metamorphosis, the first stage being 
the free-swimming nawplius. 'Tarthenogenesis occurs in many 
genera of Phyllocardia and Ostracoda." — Sedgwick. 

Order I. Phyllop'oda are small aquatic crustaceans with 
segmented bodies and leaf-like appendages. The brine shrimp, 
fresh-water Branchipus, and Daphnia are examples of the 
order. Daphnia is shelled and looks Hke a very small clam. 

The animals of this order form an important part of the 
food of fresh-water fishes. The eggs of many species can 
resist the drought, which is a valuable means of perpetuating 
them in small streams which dry up in summer. 

Order II. Ostrac'oda are small crustaceans with apparently 
unsegmented bodies enclosed in a bivalve shell, as the fresh- 
water Cypris. The abdomen is rudimentary. There are only 
two pairs of thoracic appendages, two pairs of maxillae, one pair 
of mandibles, one pair of antennae, and one pair of antennules. 
The antennae and antennules are used for locomotion. The 



CRUSTACEA 



91 



antennules are also provided with olfactory hairs. Many of 
this order are marine.^ Some, however, live in brackish or in 
fresh water. They live usually at the bottom of their aquatic 
habitat. 

Order III. Copep'oda. — As examples may be named para- 
sitic fish lice and the fresh-water cyclops. Respiration takes 
place over the entire body surface. 

The Cyclops (Fig. 65) is a small, 
white, shelless animal with elongated 
segmented body. It has a rather large 
eye in the center of its head. 

Order IV. Cirripe'dia or Barnacles. 
— These fixed, marine, shelled crusta- 
ceans are very abundant along the 
seacoast, the rocks being covered with 
them in places. Their food consists 
of small animals in the water. One 
may see thousands of barnacles snap- 
ping their food as the waves and tides 
dash over them. 

Some forms attach themselves to 
crabs, mollusks (Fig. 52), or even to 
whales, while others are true external 
parasites, sucking the juices of the ani- 
mals to which they are attached. The 
parasitic forms are extremely degenerate. 

Since they have no power of loco- 
motion by which to escape their ene- 
mies, the barnacles (Fig. 66) are pro- 
tected by shells capable of " complete 
closure." The body is flexed ventrally 

and bears six pairs of cirri, which are used in straining small 
organisms from the water and in carrying them to the mouth. 
The mouth is surrounded by a pair of mandibles and two pairs 
of maxillae. Barnacles are hermaphroditic, but cross-fertiliza- 
tion may occur. They have a metamorphosis, having first a 
nauplius and then a cypris stage, the latter developing into 
the fixed adult (Fig. 67). This order furnishes a good illus- 
tration of the principle that inactivity leads to degeneration. 




Fig. 65. — Cyclops: e, 
Eye; h, heart; eg, feet; 
/, eggs. (Clark.) 



92 



BRANCH ARTHROPODA 



The barnacles (Lepas) are found in clusters on the bottom of 
ships and often greatly impede their progress. 




Fig. 66. — Anatomy of Lepas fascicularis (Packard) : A, c, Six pairs of 
legs or cirri; /, filamentary appendages; m, mouth; s, stomach; h, openings 
of the Uver (l) into the stomach, which is represented as laid open; i, in- 
testine; a, vent; t, testis; v, vasa def erentia, one cut off; p, male appendage; 
0, ovary; e, adductor muscle connecting the two basal valves; vs, scutal 
valve; vc, carinal valve; vt, tergal valve. Enlarged twice. B, 1, Palpus; 
2, mandibles; 3 and 4, first and second maxillse. C, Nervous system: s, 
Brain, sending the optic nerves to the rudimentary eye (e), each optic 
nerve having an enlargement near the eye, i. e., the ophthalmic ganglion 
(o); between o and a are the nerves which go to the peduncle; a, nerve 
sent to the adductor scutorum; oe, commissure between the supra- and 
infra-esophageal ganglia (n) ; c, c, c, c, c, c, nerves to each of the six feet. 
Enlarged four times. (After Kingsley.) 



Sub-class II. Mal'acos'traca is composed of crustaceans of a 
definite number of segments, usually twenty — the head of five 
segments; the thorax, eight; and the abdomen, seven. These 



CRUSTACEA 



93 



segments are sometimes so fused as to puzzle one to distinguish 
twenty segments, as in the crayfish, but by regarding one pair 
of appendages to each segment one is able to count the number 
of segments present in the specimen. There is a number of 
orders under this sub-class, but only a few can be mentioned. 

Order I. Phyllocar'dia is marine. The genus Nebalia, with 
its bivalve carapace, its leaf-like thoracic feet, and biramous 




Fig. 67. — Three adult crustaceans and their larvse: a, Prawn (Peneus), 
active and free living; b, larva of prawn; c, Sacculina, parasite; d, larva of 
Sacculina; e, barnacle (Lepas), with fixed quiescent life; /, larva of barnacle. 
(After Hackel.) (From Jordan and Kellogg, " Animal Life," D. Appleton 
and Co., Publishers.) 



abdominal appendages, may be taken as an example of this 
order. 

Order II. Decap'oda. — This order consists of both marine 
and fresh-water crustaceans. It contains the best-known forms 
as well as the most useful ones to man, as the crayfish, lobster, 
shrimp, prawn (Fig. 67), and crab. As the ordinal name sug- 



94 



BRANCH ARTHROPODA 




Fig. 68. — Astacus fluviatilis. Ventral or sternal views (nat. size). 
A, Male; B, female: a, Vent; gg, opening of the green gland; lb, labrum; 
mt, metastoma or lower lip; od, opening of the oviduct; vd, that of the vas 
deferens; 1, eye-stalk; 2, antennule; 3, antenna; 4, mandible; 8, second 
maxillipede; 9, third or external maxillipede; 10, forceps; 11, first leg; 
14, fourth leg; 15, 16, 19, 20, first, second, fifth, and sixth abdominal ap- 
pendages; X, xi, xiv, sterna of the fourth, fifth, and eighth thoracic somite; 
xvi, sternum of the second abdominal somite. In the male, the 9th to the 
14th and the 18th to the 19th appendages are removed on the animal's 
left side; in the female, the antenna (with the exception of its basal joint) 
and the 5th to the 14th appendages on the animal's right are removed; 
the eggs also are shown attached to the swimmerets of the left side of the 
body. (Huxley.) 



CRUSTACEA 



95 



gests, they have ten " feet." The first pair is very large and 
armed with large strong pincers or chelce, for defense or for 
securing their prey. Their eyes are on movable stalks and 
can be withdrawn under the rostrum or beak for protection. 
The anterior thirteen segments are covered by a chitinous 
calcareous shield called the carapace. 

The Crayfish (Fig. 68) is the best known inland example 
of this order. The twenty segments may be discerned by 
counting one segment to each pair of appendages, which are 
arranged in the following order: one pair of antennules, one 
pair of antennae, one pair of mandibles, two pairs of maxillae, 
three pairs of maxillipeds, five pairs of legs, six pairs of swim- 




L N 



Fig. 69. — Longitudinal section through Astacus fluviatilis: C, Heart; 
Ac, cephalic aorta; Aa, abdominal aorta; the sternal artery (Sta) is given 
off close to its origin; 'Km, masticatory stomach; D, intestine; L, liver; 
T, testis; Vd, vas deferens; Go, genital opening; G, brain; N, ganglionic 
cord; Sf, lateral plate of the caudal fin; o, eye stalk. (Huxley.) 



merets, or nineteen pairs of appendages and a terminal segment 
without appendages, called the telson, which contains the 
vent or posterior opening of the alimentary tube. 

Its locomotion on four pairs of legs may be forward, sideways, 
or backward. Its backward locomotion by its " tail fin *' 
is probably its best and most rapid mode of locomotion. 

Digestion. — The food is seized by the cheliped and may be 
conveyed directly to the mouth, or, after being torn into bits, 
may be transferred to the pincers of the second and third pairs 
of legs and from there to the mouth. The jaws move from side 
to side instead of up and down. From the mouth the food 
passes into the esophagus, which is very short, as the stomach 
is in the head (Fig. 69). In the inner walls of the stomach 



96 



BRANCH ARTHROPODA 



Jjr--< 



are three " teeth " or hard processes which are controlled 
by muscles attached to them and to the carapace. By the 
action of these muscles the food is ground between these teeth, 

which are sometimes called the 
" gastric mill." In the poste- 
rior part of the stomach there 
is a series of filaments or stiff 
hairs which prevent any coarse 
or unground food from passing 
into the intestine. So the 
stomach is a masticating rather 
than a digestive organ. When 
the food is ground fine it passes 
into the intestine, a straight tube 
extending from the stomach to 
the vent. The food is acted upon 
by the digestive fluids from the 
glands which lie on each side 
of the stomach and whose ducts 
enter just back of the stomach. 
Digestion and absorption take 
place in the intestine. 

Circulation. — When the heart 
(Fig. 71) contracts the blood 
flows both forward and back- 
ward. Five tubes, or " arteries," 



Fig. 70. — Astacus fluviatilis. A 
male specimen, with the roof of the 
carapace and the terga of the ab- 
dominal somites removed to show the 
viscera (nat. size): aa, Antennary 
artery; ag, anterior gastric muscles; 
amm, adductor muscles of the mandibles; cs, cardiac portion of the stom- 
ach; gg, green glands; h, heart; hg, hind gut, or large intestine; Lr, liyer; 
oa, ophthalmic artery; pg, posterior gastric muscles; saa, superior abdominal 
artery; t, testis; rd, vas deferens. (Huxley.) 




carry it forward, and two, backward. These " arteries " keep 
dividing until they form minute capillaries with open ends. 
The blood runs into the irregular body spaces, or sinuses, and 



CRUSTACEA 



97 



bathes the tissues, then goes into the larger median ventral 
sinus below the thorax and abdomen, from which it is conducted 
to the gills. After being conveyed to the gill filaments, where 
it is aerated, it is returned to the heart through the pericardial 
sinus. The blood enters the heart, or dorsal vessel, through 
three pairs of openings, one on each side, a pair on the top, and 
another pair below. Valves prevent the blood from returning 
through these openings. 




Fig. 71. — Astacus fluviatilis. The heart (x 4). A, From above; B, 
from below; C, from the left side: a.a., Antennary artery; a.c, alae cordis, 
or fibrous bands connecting the heart with the walls of the pericardial 
sinus; h, bulbous dilatation at the origin of the sternal artery ; /i. a., hepatic 
artery; La., lateral valvular apertures; o.a., ophthalmic artery; s.o., superior 
valvular apertures; s.a.a. superior abdominal artery; st.a., sternal artery, 
in B cut off close to its origin. (After Huxley.) 

Respiration. — The plume-like gills are attached to the 
basal joints of the legs. They are situated in partially 
closed chambers between the body wall and the carapace. 
The water is drawn in and out by the " gill-bailers," parts of 
the second maxillae, in their vibration back and forth. In 
passing over the gills the water is separated from the blood by 
an extremely thin membrane. Through this membrane the 
carbon dioxid is thrown off and oxygen taken into the blood. 

Nervous System. — Several ganglia unite to form the supra- 
7 



98 BRANCH ARTHROPODA 

esophageal ganglion or " brain," from which a nerve cord 
passes on each side, uniting below the esophagus in a double 
(apparently single) ventral nerve cord (Fig. 69), which ex- 
tends the whole length of the body and connects the ganglia. 
We should expect to see a ganglion for each segment, but there 
are but thirteen ganglia, some of these being formed from a 
union of several. On each side of the esophagus is a large gang- 
lion; there are five more ganglia in the thorax and six in the 
abdomen. 

The stalked eyes are compound, being composed of many 
facets. The sense of touch is well developed. The surface 
of the body is sensitive and the antennae are especially adapted 
for " feelers." The sense of smell is thought to be seated in the 
hairs or setae on the antennules. 

Multiplication. — In the spring the little brown or black eggs 
may be found attached to the swimmerets of the female. 
For some time the young crayfishes, by means of hooks on 
their claws, cling to the swimmerets of the mother for protec- 
tion. 

Molting. — The young crayfish, which is of much the same ap- 
pearance as the adult, grows rapidly. Since the shell is hard 
the animal cannot enlarge except when it sheds its skin or molts, 
which it does periodically. Even the hard lining of the stomach 
is cast. Growth takes place while the new skin or shell is form- 
ing. 

Restoring Lost Parts. — Crayfishes have the power of growing 
a new leg to replace one broken off by accident or in a fight. 
This accounts for the unequal size of the chelipeds in many 
specimens. 

Habits. — Crayfishes inhabit fresh-water streams and ponds, 
lurking under stones or ledges in daytime and feeding at night. 
When the streams dry up, they dig holes in the ground until 
they reach water. These are sometimes many feet deep. 
The clay dug out around the hole is deposited in a " chimney." 
In these holes they probably live till the next spring. Some 
species do not live in the water, but burrow in the soft moist 
earth, and one species has been found in the sea. Crayfishes 
are omnivorous, eating anything they can get, but they prefer 
worms, insect larvae, and snails. 



CRUSTACEA 



99 



The protective resemblance is excellent, the colors varying from 
a delicate pink or tan to a dark green or purple. 

Use. — Crayfishes are used by the million in France, and to a 
limited extent in the United States, for food. They also furnish 
food for fishes. Raccoons, muskrats, and crows prey upon 
them. 

The lobster (Fig. 72) is marine and is very much like the 
crayfish, only much larger. Specimens weighing twenty-five 




Fig. 72.- 



-A small lobster (dorsal view) mounted on a glass so as to show 
both dorsal and ventral views. Students' work. 



pounds have been captured. Among the invertebrates the 
lobster ranks next to the oyster as an article of food for man. 

Prawns and shrimps look like our common crayfish and are 
used to some extent for food. They are small. The common 
prawn {Palcemone'tes vulga'ris) is about 2 inches long. It is 
transparent, so that the viscera can be seen through the thin 
leathery carapace. 



100 BRANCH ARTHROPODA 

Hermit Crabs (Fig. 73). — There are a number of species of 
hermit crabs which are not true crabs, but are more Uke the 
lobster and crayfish. They have the habit of backing into 
empty univalve shells which they carry about with them and 
into which they may withdraw for protection. This habit has 
resulted in a soft-skinned, reduced abdomen, with a spiral 
twist and with no appendages except a pair of hooks for hold- 
ing on to the inside of the shell. The abdomen is always hidden 
in the shell. The head, thorax, and legs project when the 
animal is active, but are withdrawn when danger approaches. 




Fig. 73. — Hermit crab {Pagu'rus) in shell, with a sea-anemone {Adam'sia 
pallia'ta) attached to the shell. (After Hertwig.) (From Jordan and Kel- 
logg, " Animal Life," D. Appleton and Co., Publishers.) 

As it grows it discards its shell and hunts a larger one. Some 
of these hermit crabs have a peculiar commensal fife with cer- 
tain sea-anemones (Fig. 73), which they carry about on their 
shells. If the sea- anemone becomes detached the crab hunts 
another and places it on its shell. The crab is protected from 
its enemies by the stinging threads of the anemone, also by 
its resemblance to the seaweed, while the anemone is assured 
of a fresh food supply by being carried from place to place by 
the crab. 

Crabs are other examples of this order. The cephalothorax 



CRUSTACEA 



101 



is much broader than that of the crayfish, and the abdomen, 
which is used only to protect the eggs of the female, is folded 
under the cephalothorax. They are great scavengers. Many 
kinds are used as food. One of the best for this purpose is the 






Fig. 74. — Successive stages of the molting of one individual of the blue 
crab, Calli'nectes sa'pidus. (G. Hay, in Doc. 580, Bureau of Fisheries.) 

edible or " blue crab " (Callinectes sapidus), great numbers 
of which are caught along the Atlantic and Gulf coasts. 
They are best liked for food just after their molting (Fig. 
74), and are then called '' soft-shelled crabs." They are 



102 BRANCH ARTHROPODA 

sometimes called " swimming crabs " because they have the 
last pair of thoracic legs flattened and paddle-like, adapted 
for swimming sideways quite rapidly. They have large sharp 
lateral spines. The strong chelipeds are adapted for cutting. 
Each of the other thoracic appendages ends in a point with no 
forceps. 

The little "fiddler-crab" lives in salt marshes along the Atlantic coast. 
The male has one big and one little cheliped, which he brandishes grotesquely 
when disturbed. 

The spider crab {Macrochei'ra) of Japan sometimes measures from 12 to 
16 feet from tip to tip of legs, but the body is only a few inches — about a 
foot — in width, making them very peculiar creatures. At a little distance 
they look like immense sprawling spiders. 

The little oyster crab, found so often in our dish of oysters, does 
no harm to the body of the oyster, but its life within the shell insures its 
food being brought to it by the currents of water made by the oyster to 
bring its own food. This is a case of commensalism^ where there is a decided 
advantage to one animal and none, so far as known, to the other, yet the 
intruder does no harm. 

Order III. Arthros'traca comprises both marine and fresh- 
water forms. The first thoracic segment, and sometimes the 




Fig. 75. — Beach flea, Gam'marus orna'tus. {Liter Smith.) 

second, is fused with the head and bears maxillipeds. The eyes 
are usually sessile. Gammarus (Fig. 75) is a fresh-water form. 
The Pill-bug, — If one searches under old boards or logs he 
will find a small gray or brownish fourteen-footed crustacean, 
truly terrestrial, with depressed body and with gills on the ab- 
dominal appendages. It is called " pill-bug " from its habit 

-. ^ See Jordan and Kellogg's " Evolution and Animal Life," p. 370. 



ARACHNIDA 



103 



of rolling up into a ball when surprised. Its protective resem- 
blance is good. Its locomotion is by crawling or running. 

Some of the marine Arthrostraca are parasitic on crabs and in 
the mouths of fishes. 



CLASS n. ARACH'NIDA 

Arachnids are arthropods with the head and thorax generally 
fused into a cephalothorax, bearing six pairs of appendages. 
The first and second pairs are for biting. Then follow four 
pairs of walking legs. There are no antennae, the eyes are simple, 
and the abdomen is apodal.^ 

The abdomen varies much. It is 
short in the spiders, long in the 
scorpions, or is fused with the 
thorax, forming a stout body in 
the mites. 

They are usually oviparous. How- 
ever, some scorpions and some mites 
are viviparous. They are generally 
terrestrial, but some live in the 
water. There is no well-marked 
metamorphosis. 

Order I. Scorpion'ida. — Scorpions 
(Fig. 76) are arachnids with long 
slender bodies ending in a poison 
fang. The head and thorax are 
fused and bear several pairs of 
jointed appendages. The abdomen 
consists of a broad anterior and a 
narrower posterior portion. There 
are several pairs of eyes. 

Respiration is by means of four pairs of lung-sacs opening 
on ventral side of abdomen from the third to sixth segments. 

Food. — They are carnivorous, feeding upon spiders and in- 
sects, which they seize with their pincers and sting to death. 

Multiplication. — They are viviparous. The mother cares 
for the young with great solicitude, carrying them about at- 
tached to her body. 

^ See Glossary. 




Fig. 76. — Carolina scor- 
pion (Bu'thus carolinia'nus) . 



104 



BRANCH ARTHROPODA 



Size. — One giant species in Ceylon is 12 inches in length, 
while American species are about 4 inches long. 

Habits and Distribution. — Scorpions are nocturnal. They 
live in tropical and subtropical countries. Their sting is 
dreaded by man, but seldom proves fatal. About twenty species 
are found in North America. 

Order II. Phalangid'ea. — The members of this order look 
like long-legged spiders, with small bodies. Closer observation 
shows that the abdomen is fused with the thorax and not 




^ Fig. 77. — Parts of a spider. 1, Under part of a spider's body: t,Thovax, 
or chest, from which the eight legs spring, and to which the head is united 
in one piece; /, fangs; p, palpi, or feelers, attached to the jaws; a, abdomen; 
b, breathing-slits; s, six spinnerets with thread coming from them. 2, 
Front of spider's head: e, Eyes; p, palpi; I, front legs; h, hasp of fangs; 
/, poison-fangs; j, outer jaws. (From Holder's "Zoology," American 
Book Co., Publishers.) 

joined by a pedicel, as in the spiders. The " harvest-man " 
or " daddy-long-legs " is a familiar example. It frequents 
shady places and feeds on small insects. 

They are a dull color, to fit their environment. So long as 
they remain motionless their protective resemblance conceals 
them very effectively from their enemies. The respiration is 
by tracheae. 

Order IIL Arane'ida, or Spiders (Fig. 77). — These are 
arachnids with unsegmented abdomen joined by a pedicel to 
the thorax. 



ARACHNIDA 



105 



Appendages. — There are two pairs of mouth-parts. The 
mandibles or chehcerse are strong and composed of two por- 
tions, the basal falx and the sharp-pointed fang, in which is a 
small opening, the outlet of the poison gland. The palpi are 




Fig. 78. — The bird-spider {Myg'ale avicular'ia) capturing a humming-bird. 
(From Holder's " Zoology," American Book Co., Publishers.) 

long and limb-like and are often mistaken for a fifth pair of 
thoracic legs. The basal joints are broad and adapted for 
chewing the food. They are called the maxillae. Then follow 
four pairs of seven-segmented legs used for locomotion. The 
spinnerets on the abdomen are homologous to paired appendages. 



106 BRANCH ARTHROPODA 

Color. — Almost all spiders are covered with hair. The color 
is partly in the skin and partly in the hair. The most common 
colors are grays and browns, but the colors are very varied, and 
in some species, as the jumping spider, they are almost as 
bright and gorgeous as those of butterflies. 

Foods and Feeding. — They are generally carnivorous, sucking 
the juices from their prey. Some spiders spin webs, others do 
not. The spider's thread is composed of many fine threads, 
each passing from the body by a separate tube and then unit- 
ing. The united thread forms a cord finer than the finest silk 
of the silkworm, hence it is often used for the " cross-hairs " 
of the telescope. 

Respiration is by lungs or lung-sacs containing bookleaf- 
like plates, and by trachese. 

Senses. — The sense of sight is well developed, but they seem 
to be shortsighted, seeing clearly only at a distance of 4 or 5 
inches. The palpi are organs of touch. 

Dimorphism. — Male spiders usually have longer legs and 
smaller bodies than the females. 

Sub-order Tet'rapneu'mones. — These spiders have four lungs 
and eight eyes. The most important members of the group 
spring upon their prey, often catching mice and small birds 
(Fig. 78). The large, dark, hairy spiders {Myg'ale) found in 
bunches of bananas belong here. The claws of the mandibles 
or jaws work up and down instead of from side to side. 

The trapdoor spiders (Cteni'za) of the Southwest dig tunnels 
in the soil, line them with silk, and cover them with a close- 
fitting hinged lid. 

Sub-order Dipneu'mones. — The members of this sub-order 
have two lungs and a pair of trachese. This group includes 
the majority of living spiders. 

The ground spiders (Dras'sidce) do not spin a web, but hunt their prey 
at night. Many species make silken tubes in which they lay their eggs or 
hide when molting or in winter. An eastern species lives in a bag of silk 
hidden under stones. 

The tube-weavers (Clubion'idce). — These are also species which spin no 
web. In summer they live in flat tubular nests on plants, sometimes 
in rolled leaves. In winter they live in tubular nests under bark and 
stones. 

The Funnel Web Weavers (Agalen'idce) . — They weave a concave sheet 
of silk with a funnel-like tube on one side, and with threads extending in 



ARACHNIDA 107 

all directions attached to blades of grass for support. In the morning dew 
these webs form a shimmering silken sheet. The spider runs about on 
the upper surface of the " sheet " and catches any insects which light upon 
it. The tube or hiding place opens below, so that the spider can escape if an 
enemy appears upon the web. These are long-legged brown spiders, of 
which the common grass spider is a familiar example. 

The "curled-thread weavers" are of two kinds, those which spin regular 
webs and those which spin irregular webs. The curled thread is composed 
of silk spun from a special organ, the cribel'lum, in front of the spinnerets. 
It is combed into shape by means of stiff hairs called the calamis'trum on 
the metatarsus of the hind legs, as the spider moves the hind legs rapidly 
back and forth. 

Those spiders which spin irregular curled threads (Dictyn'idae) usually 
make variously shaped webs on fences, under stones, in rotten logs, or upon 
plants having clusters of small flowers like the golden-rod. 

There are but two genera of these spiders which spin regular webs 
(Ulobor'idje) . The ' ' triangle spider ' ' is found all over the country in pine 
woods. Its web is usually stretched between the twigs of a dead branch 
of pine or spruce, and consists of four plain radiating lines and a series of 
double cross-lines. The spider, which rests near one of the twigs from which 
a strong line is drawn to one of the other twigs, pulls the web tight, so that 
the cross-lines are separated as far as possible. When an insect lights 
upon one cross-line the spider suddenly lets go, so that the whole web springs 
forward and the insect becomes tangled up in the other cross-lines. 

The cobweb v/eavers (Theridi'idce) build their webs, which are ap- 
parently only a shapeless maze of threads, in the corners of rooms — as the 
house spider — or out in the fields between the leaves of bushes, or in the 
fence corners, or among rocks. They are generally rather light colored, 
small, and soft. They live in their webs, hanging by their feet, with the 
back downward. The cocoons, several of which are made in one season, 
are soft and round and hang in the web. 

The orb weavers (Epei'ridce) construct some of the most wonderful 
homes built by any animal. First, there is an irregular outer framework of 
supporting lines; then there is a number — from twelve to seventy — of dry 
and inelastic lines radiating from the center. There is an inner spiral of 
these inelastic threads which begins at the center and winds outward. 
The rings of this spiral are about as far apart as the spider can reach. 
Its use is merely for support. The spider then begins at the outermost 
part of the web and spins an outer spiral of sticky elastic threads, winding 
inward, the concentric circles being close together. As it becomes neces- 
sary, jn forming this outer spiral, the threads of the inner spiral are de- 
stroyed. When an insect touches one of the outer sticky threads the thread 
not only sticks to it, but it stretches so that the insect becomes tangled up 
in the other circles, which is all the easier to do since the threads are so close 
together. Many species strengthen the web by spinning a zigzag ribbon 
across the center. The making of the entire web seems to be done alto- 
gether by feeling and can be done in the dark as well as in the daylight. 

Most of the orb-weaving species have large, nearly spheric abdomens and 
stout legs, sometimes " with humps and spines." These spiders are often 
brightly colored, the colors of the abdomen being arranged in a triangular 
or leaf-shaped pattern. Some species live near the center of the web, 
hanging head downward, others hang back downward near one edge of the 
nest. In some species the male is smaller than the female. 



108 



BRANCH ARTHROPODA 



The crab spiders {Thomis'idoe) are so-called because of their short broad 
form and peculiar habit of walking sidewise or backward. " They spin 
no webs, but lie in wait for their prey."^ Some brightly colored species 
conceal themselves in flowers. Their protective resemblance is so good 
that insects visiting the flower often light within reach of the spider before 
seeing it. They live about plants and fences and hibernate in winter under 
stones and bark. 

The jumping spiders (At'tidce) have stout bodies and short legs, bright 
colors, and conspicuous eyes. They jump quickly sidewise or backward 
for a long distance. They make no webs except those in which they hiber- 
nate or lay their eggs. 

The Running Spiders (Lycos'idce) . — These are the familiar hairy dark- 
colored spiders found under stones and logs. They depend upon their 
speed for the capture of their prey and run very swiftly. They resemble 
in appearance and habits the so-called tarantulas of the Southwest, but are 
smaller. The claws of their mandibles move horizontally. Their eyes are 




Fig. 79. — Female spider with young ones. (Cooper.) 

of different sizes. Some of these spiders build tubular nests in the ground 
and line them with silk. They sometimes conceal the entrance with leaves 
and sticks. They often drag the egg-sac, a large gray ball, after them. In 
genus Lyco'sa the young (Fig. 79) climb upon their mother's back. The 
female of another genus, Dolome'des, carries the egg-sac " in her mandibles 
until the young are ready to hatch, when she fastens the sac in a bush and 
spins a web of irregular thread about it in which the young remain for a 
time." 



Order Acari'na. — These arachnids have stout bodies, there 
being no apparent segments, the abdomen being united with the 
cephalothorax. There is no heart nor blood-vessels. The res- 
piration is performed by means of tracheae. They are generally 
oviparous; some are viviparous. Many are parasitic (Fig. 80). 

^ Comstock. 



ARACHNIDA 



109 



The mouth parts are more or less united to form a beak. The 
common red mite sucks the juices of the house plants which it 




Fig. SO. — The chicken mite {Dennanys'sus galli'nce): o, Adult; b, tarsus; 
c, mouth parts; d and e, young. All much enlarged. (Osborn, U. S. Bu- 
reau of Ent., 1907). 




Fig. 81. — Cattle tick (enlarged). (After Salmon and Stiles.) 

infests. One mite (Dem'odex) is parasitic in the hair-follicles of 
the dog, cat, sheep, cow, horse, and man. Another mite 



110 



BRANCH ARTHROPODA 



(Sarcop'tes scah'ei) is the itch mite, causing the disease called the 
itch. Still another is called the cheese-mite. 

Ticks (Ixo'des) are parasitic, blood-sucking Acarina which 
attack man and other mammals. They do not exceed a centi- 
meter in length, the males being the smaller. The so-called 
" Texas fever " of cattle is transferred by the common cattle 
tick (Fig. 81). 




Fig. 



82. — Horseshoe or king crab (slightly damaged on left), 
specimen.) 



(From 



Order IV, Xiph'osu'ra. — The Lim'ulus, or horseshoe crab (Fig. 
82) , is a marine arachnid living on the bottom of the sea in . 
shallow water, creeping along in the mud and sand and feeding 



MYRIAPODA 



111 



on worms. The body has a chitinous covering. The cephalo- 
thorax is arched and bears the large compound eyes and two 
simple eyes. The abdomen is almost hexagonal and ends in a 
long caudal spine. On the ventral side of the cephalo thorax 
are six pairs of appendages, used for securing food and for 
locomotion. The last pair, the operculum, is broad and leaf- 
like and covers the five pairs of leaf-like branchial appendages 
of the abdomen. These appendages are for respiration. The 
shape of the body, its hard covering, marginal spines, and its 
color, which harmonizes with its environment, afford it ample 
protection and defense. 

There are several other orders, but these will suffice for our 
purpose in the present work. 



CLASS m. MYRIAP'ODA 

The name indicates myriad footed, hence the common name, 
thousand-legs. A myriapod is a worm-like tracheate arthropod 
with a distinct head, a round or flattened 
body composed of many similar segments, 
to each of which is attached one or two pairs 
of appendages. Myriapods have one pair 
of mandibles, one pair of antennae, and 
numerous ocelli. " A few species are injur- 
ious to agriculture, while others are to be 
classed among our friends." 

Order I. Chilop'oda. — ^These are myria- 
pods with the body flattened, with fifteen 
to one hundred and seventy or more seg- 
ments, each bearing a single pair of legs, 
and with long, many jointed antennae (Fig. 
83). The mouth parts are adapted for bit- 
ing. The opening of the poison gland is 
on the first pair of legs, which are used 
with the mouth parts. This order includes 
the centipedes, as Litho'hius, common under 
stones. The bite of the true centipede 
(Scolopen'dra) is fatal to insects and to 
other small animals, their prey, and painful or even dangerous 
to man. 



Fig. 83.— A centi- 
pede. 



112 BRANCH ARTHROPODA 

Order II. Diplop'oda. — These are myriapods with dorsally 
convex bodies. Each apparent segment, beginning with the 
fourth or fifth, bears two pairs of appendages. There are no 
poison fangs. The antennae are short and few jointed. This 
order includes the miUipeds. An example is lulus. They 
are found under old stumps or about rotten logs. Their food 
consists usually of decaying vegetable matter, but some forms 




Class collecting insects. 



feed upon growing plants, otherwise they are harmless. They 
have a habit of rolling up into a helix-like coil when disturbed. 
They are bisexual. When hatched the young have but three 
pairs of legs. " By successive molts new segments and append- 
ages are added " until the adult form is reached. 

CLASS IV. INSEC'TA 

This class of Arthropoda comprises a very large number of 
species. Three hundred thousand, according to Kellogg, are 
known. 



INSECTA 



113 



Habits and Habitat. — Insects vary in their habitat. Most 
of them are terrestrial, some are aerial, others are aquatic, a 
few even being marine, while still others are subterranean. 



iabrom \D^ 




A 

I SpiroeJl 



'Pleurife 



Fig. 85. — External anatomy of Calopte'nus spre'tus, the head and thorax 
disjointed: up, Uropatagium; /, furcula; c, cercus. (Drawn by J. S. 
lungsley.) (From Packard's "Zoology," Henry Holt & Co., Publishers.) 



Some are diurnal, as our common butterflies; others are noc- 
turnal, as the bed-bug; some, crepuscular, as the moths. Some 
are solitary; others gregarious, or social, as the ants and bees. 

Plan of Structure (Fig. 85). — The insect body is divided into 
three well-marked regions — ^the head, thorax, and abdomen. 
8 



114 



BRANCH ARTHROPODA 



The head bears the compound eyes and simple eyes (when they 
are present), one pair of antennae, and three pairs of mouth 
parts, which vary according to the character of their food. 
Hence the mouth parts may be adapted for chewing, lapping, 
sucking, or piercing — " all referable back to the chewing type. 
These are, in turn, modified legs."^ 

The thorax has usually three well-marked segments — pro- 
thorax, mesothorax, and metathorax — as in the grasshopper. 
Each segment bears a pair of jointed ventral legs. The two 
pairs of wings, when present, are outgrowths of the dorsal por- 




Fig. 86.—" Look out!" 

tion of the meso- and metathorax. Sometimes there is but 
one pair, and in a few cases none. 

The abdominal segments vary in number and usually bear 
no paired appendages except, sometimes, on the terminal seg- 
ments. 

Covering. — Over the greater portion of the surface of the body 
the cuticle or external layer of the skin is made firm and horny 
by a substance called chitin. This forms an exoskeleton for the 
protection of the soft parts within, and, by its rough interior 
surface, provides points of attachment for the numerous small 
but strong muscles. 

1 Kingsley's Hertwig, " A Manual of Zoology." 



INSECTA 



115 



Those portions of the cuticle which do not contain much 
chitin are easily bent, thus permitting motion between the 
segments of the body and of the appendages. 

All insects have hairs scattered more or less abundantly or 
regularly over the body. In Lepidoptera the hairs are modified 
into scales, as is shown on the wings of a butterfly, where " all 
the gradations from hair to scale can be found by going from 
the base out to the distal area of the wing."^ 

Self-defense (Fig. 86) is by various methods and organs, 
which will suggest themselves to the student from his past 
experience. When insects cannot sting or bite, they often 




Fig. 87. — Al'aus ocula'tus and larva, showing eye-spots. (After Harris.) 



defend themselves by threatening attitudes. In some cases 
one is reminded, at first sight, of a snake's head, and retreats 
in terror. The " eye-spots " (Fig. 87) and " horns " (Fig. 88) 
on many insects are probably for the purpose of terrifying ap- 
pearance. 

Protective Coloration, — Insects attract attention by the 
variety and intensity of their colors and by their numerous, 
interesting, and often beautiful color-patterns. Many natural- 
ists believe, and have confirmed their opinions by observation 
and experiment, that the variety of color and color-patterns of 

1 Kellogg, p. 592. 



116 BRANCH ARTHROPODA 

insects and of other animals is indirectly due to two causes: 
first, the advantages given to the individual or species in the 
struggle for existence by these specific colors and color-patterns, 
which — as in the case of the gray moth on the tree-trunk or 
the katy-did among the green leaves — helps to conceal them 



'^^flHP^^l^^li^^B^^SM^^^^^HH^^^^SHH^^aiNl^EJF^SE^^^^ 



Fig. 88. — Larva of regal walnut moth {Cither o'nia rega'lis) extended (two- 
thirds nat. size). (Photographed from life.) 

from their enemies by affording protective resemblance, or — as 
in the case of the bumble-bee or the milkweed butterfly — to 
warn the enemy of the danger of sting or of the disagreeable odor 
and taste. The advantage gained is easy to be seen in each 




Fig. 89. — Pupa of regal walnut moth (three-quarters nat. size). (From 

life.) 

case. They believe that these particular color-patterns are 
due, in the second place, to gradual development " through 
natural selection of naturally occurring, advantageous varia- 
tions." 

The direct cause of color may be chemical, depending on the 



INSECTA 



117 



chemical composition; or physical, depending upon the structural 
or physical make-up; or it may be due to a combination of 
both of these. In the most highly colored group of insects, 
the Lepidoptera, the color is due to the chemical substances 
(pigment granules), to the structural character of the scale 




Fig. 90. — The protective resemblance of the leaf -butterfly (Kal'lima). 
(Holder, after Wallace.) 



walls (striae), and to the overlapping (lamination) of the scales 
laterally, as well as to the overlapping of the tips of the scales 
in one row over the bases of the scales of another row. 

" The blacks, browns, yellows, and dull reds of butterflies and 
moths are produced chiefly by the pigments (chemical colors), 
while the brilliant metallic colors, the iridescent blues and 



118 BRANCH ARTHROPODA 

greens, . . . are due to the structural or physical make-up of the 
scale covering."^ 

Variable Protective Resemblance. — Often the different indi- 
viduals of the same species are of slightly different colors, the 
colors varying to harmonize with the particular environment 
of the individual during its development, being fixed in the 
adult. 

Special protective resemblance (Fig. 90) is illustrated by 
Kallima, which resembles a dead leaf, and Phyllium, resembling 
a green leaf (Fig. 91), and, more commonly, by the measuring- 
worm, as it holds the body out stiff, imitating a short or broken 
twig. Thus in many cases " the insect's appearance simulates 
in more or less nearly exact ways some par- 
ticular part of the habitual environment." 

Warning, colors are possessed by many 
insects having a special organ of defense 
— as the sting of that wonderful little 
stimulator, the hornet — or a disagreeable 
taste or odor, as that of the milkweed or 
" monarch " butterfly {Anosia plexippus) 
(Fig. 92, a). Other examples of insects 
having conspicuous or warning colors are 




¥ 



s^\W the black and yellow wasps and bees, the 

^vb/ lady-bird beetle, and the swallow-tail but- 

V terflies. Many others might be mentioned. 

Fig. 9i. —PhyV- Since the bodies of insects are soft, one 
Hum siccifo'hwn ^^^ easily see why these conspicuous colors 
ieeds on leaves, and „ -^ , / a • i x i 

mimics fresh leaves, ^'^e ot natural advantage. A smgie stroke 
(Holder.) of the beak of a bird might prove fatal 

to any of them. The bird must learn by 
experience that the insect is armed or distasteful, but if the 
insect is conspicuously colored, it will be noticeable and easily 
remembered, so that the bird will not attack another of this 
brightly colored kind. Hence the species will be perpetuated 
and the characteristic colors handed down to the next genera- 
tion, or, in other words, " preserved and accumulated by natural 
selection." 

Alluring or directing colors or forms may be found among in- 

' Kellogg. 



INSECTA 



119 



sects, according to Poulton. The apical portion of the fore- 
wing and the hind portion of the posterior wing are especially 
marked with borders or eye-like spots, and are often prolonged, 
as in the swallow-tail butterfly, into antennae-like processes or 
tails. These, resembling the head with eyes and antennae, 
direct the stroke of the enemy to this part. The insect thus 
escapes with the loss of the tip or a scrap of the wing, thus saving 
its head or its soft body. 




Fig. 92. — a, Monarch butterfly( A?io'sia plexip'pus), distasteful to birds. 
b, Viceroy {Basilar' chia archip' pus) , which mimics it. (From Kellogg's 
■'Zoology," Henry Holt & Co., Publishers.) 

Mimicry. — The viceroy butterfly (Fig. 92, 6) imitates, uncon- 
sciously, of course, the common '' monarch " or milkweed 
butterfly, since the latter is seldom eaten by birds, owing to a 
disagreeable taste or odor. Many bees are mimicked by flies, 
and distasteful beetles by other beetles. 

Muscular System and Locomotion. — Locomotion may be in 
any one or all of three ways — running, jumping, or flying. The 



120 BRANCH ARTHROPODA 

muscular system varies widely in the different forms. In the 
caterpillars there is a "simple worm-like arrangement of 
segmentally disposed longitudinal and ring muscles," while in 
the more active forms, as flies and bees, the muscular system is 
complicated. The muscles are composed of fine, cross-striated 
fibers, forming masses of various sizes, and are attached to the 
rough inner surface of the exoskelton. The muscles are trans- 
parent and have great contractile power. 

Digestive System. — The alimentary tube (Fig. 93), which may 
be coiled much or little, varies greatly. It is about the length 



•nctalgliineL 

ctum. 




Fig. 93. — Internal anatomy of Calopte'nus fe'mur-ru'hrum: at, Antenna 
and nerve leading to it from the " brain " or supra-esophageal ganglion 
(sp); oc, ocelli, anterior and vertical ones, with ocellar nerves leadmgto 
them from the " brain "; ce, esophagus; m, mouth; lb, labium or under lip; 
ij, infra-esophageal ganglion, sending three pairs of nerves to the man- 
dibles, maxilla?, and labium respectively (not clearly shown in the engrav- 
ing); sm, sympathetic or vagus nerve, starting from a ganghon resting 
above the esophagus, and connecting with another ganghon {sg) near the 
hinder end of the crop; sal, salivary glands (the termination of the salivary 
duct not clearly shown by the engraver); nv, nervous cord and gangha; 
ov, ovary; ur, urinary tubes (cut off, leaving the stumps); ovi, oviduct; 
sb, sebaceous gland; he, bursa copulatrix; ovt' , site of opening of the oviduct 
(the left oviduct cut away) ; 1-10, abdominal segments. All other organs 
labeled in full. (Drawn from his original dissections by Mr. Edward 
Burgess.) (From Packard's " Zoology," Henry Holt & Co., Publishers.) 

of the body in carnivorous forms, and longer in the herbivorous 
insects. It consists of a mouth, esophagus, crop, gizzard (the 
chitinous lining of which is toothed for grinding the food), a 
digestive stomach, and an intestine. There may be one or two 
pairs of salivary glands, and usually two or more pairs of 
gastric cseca containing glands supposed to supply digestive 
fluids. The intestine usually consists of a small intestine and a 
large intestine, the two regions of the latter being the colon and 
the rectum. The Malphighian tubules, fine tubes connected 
with the intestine at the beginning of the rectum, take the place 



INSECTA 



121 



of kidneys. There is no liver. The entire viscera are en- 
veloped in the " lat body." The anal opening is in the last 
segment of the abdomen. 

Insects feed upon the juices, leaves, or even the wood of 
plants, or are parasitic or predaceous upon various forms of 
insects, and upon other animals as well. Some live upon de- 
caying organic matter. 




Fig. 94. — Ideal transverse section of an insect: h, Dorsal vessel; i, 
intestine; n, ventral nerve-cord; t,t, stigmata leading into the branched 
tracheal tubes; w, w, wings; a, coxa of one leg; b, trochanter; c, femur; 
d, tibia; e, tarsus. (After Packard.) 

The circulatory organs are extremely primitive in character. 
The heart or dorsal vessel extends through the abdomen just 
underneath the dorsal surface. It is partially divided by valves 
into chambers, the number of which varies. The anterior 
chamber extends into or near the head and is sometimes called 
the aorta. The heart chambers pulsate rhythmically, from the 
posterior one forward, and force the blood out into the body 
cavity. There are no veins or arteries, so it flows through the 
sinuses or open spaces between the organs, bathing the tissues, 
and finally bathing the walls of the alimentary tube, where it 



12!^ 



BRANCH ARTHROPODA 



takes up the food supply and then re-enters the heart through 
the side openings. It does not supply the tissues with oxygen, 
since it receives only enough for its own use. 

Respiration is carried on by a series of air-tubes called 
tracheae. These tubes are interbranching and penetrate to 
every portion of the body. The air enters them through a 
pair of stigmata or pores, one on either side of each segment. 
The functions of these tracheae are to take up oxygen from the 
air and to distribute it to the tissues of the body, since this is 
not done by the circulation of the blood, and to collect and carry 
off the carbon dioxid. 

Insects which live in water either come up to the surface to 
breathe and, in some cases, to take down a supply of air held 
on the outside of the body by a fine pubescence, or they are 
provided with tracheal gills which will enable them to breathe 
air mixed with water. Gilled insects, of course, do not have to 
come to the surface to breathe. 

The Nervous System.— Besides the central or ventral (Fig. 
93) nervous system (see Branch Arthropoda), insects have 
a small and varying sympathetic nervous system (Fig. 93), 
consisting of a few small ganglia sending nerves to the automatic- 
acting visceral organs. Commissures connect the sympathetic 
system with the brain just at the origin of the subesophageal 
commissures. 

Touch. — The sense of touch is located in the " hairs " dis- 
tributed over the various parts of the body, but most numerous 
on the feelers. 

Taste is located on small papillae or in pits on the mouth- 
parts, particularly on the tips of the palpi and on the upper wall 
of the mouth. 

Smell is probably the most used sense of insects. The 
organs of this sense are minute papillae and " microscopic pits " 
on the antennae and mouth parts. It has been proved that 
most insects find their food by this sense. " It is believed that 
ants find their way back to their nests by the sense of smell and 
that they can recognize by scent, among hundreds of individuals 
taken from various communities, members of their own com- 
munity."^ 

' Kellogg's " American Insects." 



INSECTA 123 

Hearing. — Many insects have sound-producing organs and 
auditory organs ; and it has been proved by experiment that they 
hear. The ear of the grasshopper or locust, a small tympanic 
membrane, is situated at the anterior end of the abdomen, while 
that of the katy-did and cricket (Fig. 95) is situated on the tibia 
of the fore-leg. There is a special auditory ganglion. The 
mosquito has its auditory organs in the antennae in the seg- 
ments next to the basal ones, through which the sound or vibra- 
tions are carried by many fine auditory hairs, and from which the 
auditory nerves lead to the "brain." It is thought that the 
male mosquito finds his mate by her song. 

Sight. — Insects usually have both simple and compound 
eyes, though either kind may be found alone; and a few in- 
sects are blind by degeneration. The ocelli, or simple eyes, 
are usually three in number and form a little triangle on the 




Fig. 95. — The front leg of the cricket enlarged, showing the ear at a. 

top of the head. Each of them is supplied with a special nerve 
from the " brain." It is thought that the ocelli can do little 
more than distinguish light from darkness and that their range 
of vision is restricted to an inch or two in front of the head. 
The compound eyes, two in number (see Fig. 84), are usually 
large and conspicuous, often composing more than two-thirds 
of the entire head. Each compound eye presents from twenty 
to several thousand polygonal facets, or windows, which, alto- 
gether, form the cornea. It is thought that the range of vision 
of the compound eyes is two or three yards. The larger the 
eyes, the wider will be the range of vision, while the smaller 
and more numerous the facets, the sharper and more distinct 
will be the image. Experim^ent and study of the structure of the 
eye, says Kellogg, " indicate that, at best, the sight of insects 
cannot be exact or of much range." 



124 BRANCH ARTHROPODA 

The psychology of insects is a very interesting study. Whether 
the activities of insects are due to reflex action, instinct, or 
intelligence can be better determined when studying the various 
species, but one will surely find that insects, as well as being the 
most numerous and various, are also the most interesting and 
wonderful of all the classes of invertebrates. 

Multiplication is by eggs, of which many are deposited in 
various places. Some are placed on or in another animal's 
body, others on leaves or stems of plants, which serve as food 
for the young. However, some insects, as the Aphides, show 
parthenogenesis, i. e., they are supposed to produce young 
from unfertilized eggs. 

Metamorphosis. — Insects pass through a more or less com- 
plete series of changes, called metamorphosis. The larvse, 
whose business it is to feed and grow, are called by various names, 
as caterpillars, grubs, nymphs, and maggots. Since the larvse 
are wingless they are placed in different relations to their 
environment from those of the adult, and hence often have 
special larval organs. The larval stage is followed by a quiet 
stage called the pupa (Fig. 89). In this condition many in- 
sects pass the winter and come forth in the spring as adults 
or imagoes, the reproductive stage. Others remain in the 
pupa stage but a few weeks, thus giving time for two or more 
broods in a season. "Parthenogenesis occurs in Hymenoptera 
and Hemiptera." — Sedgwick. 

Parasitism is common in insects. Parasites may be ex- 
ternal or internal. The natural consequence of a parasitic life 
is degeneration, as is seen in lice and fleas, whose ancestors were 
winged insects. 

Environmental Influences. — Insects are affected by tempera- 
ture. They become active with the rise of temperature in the 
spring, and some become dormant or hibernate as the tempera- 
ture declines in fall and early winter. Most of them die with 
the advent of frost. The direction and velocity of the wind 
is a factor in insect life, especially in its distribution. 

The amount of precipitation will influence the amount 
and kind of vegetation, which determines to a large extent the 
number and kind of insects. Certain kinds of precipitation, 
as hail, for example, or floods, would destroy large numbers of 
insects. Any environmental factor would increase or decrease 



INSECTA 



125 



the activity, food, enemies, dispersal, migration, mentality, or 
other phenomena connected with animal life. 

Geologic Distribution. — Insects of some kind have existed 
for a long time geologically, insect remains being found in the 
lower and upper Silurian. 

Economic Importance. — Insects devour our crops, carry dis- 
ease, annoy us when awake and prey upon us when we sleep, 
injure or destroy our stock, infest our orchards, and in some 
countries the white ants do much damage to dwellings. The 
damage to our American crops has been estimated at the enor- 
mous sum of $700,000,000 in one year. But when we remember 
that insects are also dangerous 
to health and life, how much 
more is the number of injuri- 
ous insects to be deprecatedv 
Kellogg says, " Mosquitos help 
to propagate and are almost 
certainly the exclusive dis- 
seminating agents of malaria, 
yellow fever," and other dis- 
eases; " house-flies aid in 
spreading typhoid fever and 
other diseases; fleas are agents 
in distributing the germs of 
the bubonic plague." Howard 
says the germs of the disease 
known as '' pink-eye " are car- 
ried by very minute flies of the genus Hippelates 
are known to spread other diseases (Fig. 96). 

However, some insects are valuable to man. The honey-bee 
makes honey; other insects furnish galls for ink; others, dye- 
stuffs, such as cochineal; while others serve as scavengers, 
and the silkworm (Fig. 97) furnishes our finest clothes. The 
bumble-bee fertilizes the clover blossoms, other insects cross- 
fertilize the flowers of many plants, and many serve as food for 
birds. Thus, while some insects are very harmful to us, others 
are very valuable to us. If we (with the help of the birds) 
exterminate those which are injurious and protect those which 




Fig. 96. — Tsetse fly, which causes 
a disease of cattle in Africa, en- 
larged. (L. O. Howard.) 



Other insects 



126 



BRANCH ARTHROPODA 



are beneficial, our crops will be the larger and more profitable, 
and our bodies more secure from disease. 

Classification. — Entomologists vary in their opinions as to 
the number of orders into which the Class Insecta should be 
divided. Packard's "Guide" (1883) gives eight orders, while 
Comstock's "Manual" (1895) and Kellogg's "American Insects" 
(1905) each give nineteen orders. Kellogg says, " In the first 
place the author believes that this classification^ best represents 
our present knowledge of insect taxonomy ; in the second place, 




Fig. 97.— Adult silkworm: 1, Head; 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, rings; 
11, horn; 13, three pairs of articulated legs; 14, four pairs of abdominal 
or false legs; 15, a pair of false legs on the last ring. (Farmers' Bull. 
165, U. S. Dept. of Agriculture.) I'he silk glands of caterpillars are ho- 
mologous with the true salivary glands of other insects. — Folsom. 

this is the classification taught by nearly all the teachers of 
entomology in America." 

Students wishing to study insects in detail should consult 
either Comstock's or Kellogg's large work on insects. 



ORDER I. AP'TERA OR THYSANU'RA 

These are small or minute wingless insects which undergo 
no metamorphosis. The body is covered with hairs or scales. 
There are several pairs of rudimentary abdominal appendages, 
probably vestiges of abdominal legs in ancestors. The mouth 
parts are adapted for biting. " Their internal systems of organs 
have a segmental character corresponding to the external seg- 
mentation of the body."" They live in sugar boxes and pan- 

1 Comstock's classification. ^ Kellogg, p. 59. 



EPHEMERIDA 



127 



tries or under leaves, and in the spring they are sometimes 
found m large numbers on the surface of pools of water or upon 
the snow. 

, Campo'dea staphyli'nus, which is regarded as the most primitive living 

TAr-z uvtiei^gsr'-" • '"* """• "•>'- "^^Sst 

soft and delicate. It is widely dis- f— 
tributed. 

The "fish-moth" {Lepis'ma sac- 
chan'na) of the house (Fig. 98), which 
is neither a moth nor a fish, is sil- 
very white, with a yellowish tinge 
on antennae and legs. It is about \ 
■ inch long, has three long caudal ap- 
pendages, and feeds chiefly upon 
sweet starchy materials, often at- 
tackmg starched clothing and the 
paste of wall-paper and book-bind^ 
ings. It may be gotten rid of by 
sprmklmg fresh pyrethrum powder 
m_ the places infested or by spraying 
slightly with nicotin or formalin. 

The "spring-tails" {Collem'hola) 
have a forked spring attached to the 
next to the last segment of the ab- 
domen, by means of which they leap 
from a few inches to a foot in the air. 
The " snow-fleas " collect in large 
numbers on the snow in spring. 
They are often a cause of great an- 
noyance where maple sugar is made. 

Surely the insects of this Fig. ^s.— Lepis'ma sacchari'na, 

order, by their simplicity of enlarged. (L. O. Howard, U. S, 
structure and their similarity ^^^^P^- of Agriculture.) 
of somites, show their worm ancestry, though some species 
show much more complexity of structure. It will be interest- 
ing for the student to consider how, from such a generalized 
primitive form as Campodea staphylinus, nature can produce 
by modification of parts, an insect of highly complex structure! 

Order ii. ephemer'ida 

The May-flies, in the adult form, are insects of a day, but 
they pass two or three years in the larval stage. When they 
emerge from their larval condition into their winged form 




128 BRANCH ARTHROPODA 

they come forth in myriads along streams. The authors saw 
their dead bodies piled a foot deep on an Illinois river bridge 
just under the electric lights. So thick were they that workmen 
came next day and shovelled myriads of them into the river. 
They are fragile, soft skinned, and long bodied, with four gauzy 
wings, of which the anterior pair is much the larger. The 
abdomen ends in long thread-like anal projections. The 
mouth parts are rudimentary. Indeed, the adults are said to 
take no food, but to reproduce and die. The eggs are laid in 
the water. Soon appear tiny, soft-bodied, wingless nymphs, 
bearing leaf-like fringed gills arranged segmentally along the 
sides, and two or three many jointed anal appendages. They 
have strong legs and can both swim and walk. They lie on the 
bottom of streams, and, with their powerful mandibles which are 
adapted for biting and chewing, catch and devour other insects. 
They eat plants also, and are themselves prized as food by many 
kinds of fishes and other aquatic animals. 

After the ninth molt (some species have twenty-one) the wing- 
pads begin to develop. The nymph continues to grow and to 
molt, until finally it leaves behind its '' water-nymph skin " 
and comes forth a winged May-fly. Again it sheds its skin, 
it may be within a few minutes or within twenty-four hours, a 
thin layer coming off even from the wings. This is the only 
known instance of an insect molting after acquiring its wings. 

ORDER III. PLECOP'TERA 

The stone-flies are comprised of a single family, the Per'lidce. 
These grayish or brownish insects (Fig. 99) are ^ to 1| inches 
long and have four large membranous wings, but the posterior 
pair folds up like a fan when not in use. Unlike the dragon- 
flies, in which the anterior and posterior wings are about equal 
in size, the posterior wings are much wider than the anterior 
ones. The mouth parts are adapted for biting, but poorly so 
as compared with those of the dragon-fly. The adults probably 
eat little. The long antennae are many jointed and the abdomen 
is often furnished with a pair of many jointed bristles or fila- 
ments. The 5000 or 6000 eggs are probably well scattered in 
the swift current before dropping to the bottom. The meta- 



ODONATA 



129 



morphosis is incomplete. The nymphs, Hke those of the 
dragon-fly, are aquatic. They are provided with gills. Those 
who advocate the aquatic ancestry of insects believe that the 
spiracles are the openings left when the gills were lost, but certain 
species of stone-flies retain their gills — ^though shrivelled and 
probably functionless — and have wholly independent spiracles.^ 




Fig. 99. — A, Stone-fly. B, A nymph of a stone-fly. (Comstock.) 



The larvae of stone-flies are flat and cling closely to the surface 
of stones in the swiftest portion of the stream. They cannot 
live in stagnant or foul water. Their resemblance to a fossil 
is almost perfect. This resemblance is their protection from 
their enemies, the fishes. These larval stone-flies are good bait 
for trout. 

ORDER IV. ODON'ATA 

Dragon-flies.— To this order again belongs^ a single family,' 
the Libellu'lidce, or dragon-flies (Fig. 100). They have many 
common names, as " mule-killers," "snake-doctors," and 
" devil's darning-needles," but, in spite of these terrifying names, 
they are all perfectly harmless to man. 

1 Kellogg, p. 72. 

2 Kellogg includes the damsel flies. 

3 Comstock, p. 90. 



130 



BRANCH ARTHROPODA 



The four finely netted membranous wings of the adult dragon- 
fly are long, narrow, strong, and nearly equal. If unequal, the 
posterior wings are the larger. Each wing has a joint-like struc- 
ture near the middle of the front margin. Their mouth parts 




Fig. 100. — Dragon-flies in the larval, pupal, and imago state. 
(After Tonney.) 

are adapted for biting. Their compound eyes are very large 
and the antennae short. The metamorphosis is incomplete. 
The eggs are laid in water or attached to aquatic plants. 
They soon hatch, and the larvae (Fig. 100), called nymphs, 
live a predatory existence. They lie in wait for their prey. 



ISOPTERA 131 

" The fierce face of the young dragon is all concealed " by its 
extensible lower lip, which folds up. With their strong jaws and 
legs dragon-flies secure and devour their prey. They devour vast 
numbers of larval mosquitos and are thus of great use to man. 
Finally, the full-grown nymph creeps up some stem, and the 
winged form of the imago or adult dragon-fly breaks through the 
old skin and flies away into the air and sunshine to enjoy its 
aerial life until the falling temperature ends its existence. 
These beautiful creatures may be called creatures of the air, for 
they actually feed upon the wing and may sometimes be seen 
poised in mid-air as if resting. The adult devours many gnats 
and mosquitos. There are two types of dragon-flies, one 
which keeps its wings horizontal and one which folds its wings 
together vertically over the back.^ 

The breathing of the nymphs is peculiar. " The caudal end 
of the alimentary canal is lined with tracheae, and water is 
alternately drawn into and expelled from this cavity. The 
water may be expelled with such force as to propel the body 
forward. So this has a locomotive function also." 

Order v. isop'tera 

The Termites (Fig. 101), or so-called "white ants," are abun- 
dant in the tropics, but less so in the United States. Where 
they are numerous they become pests, destroying houses, furni- 
ture, or anything made of wood. They are not ants, as may be 
seen by their structure. 

The body is always soft and usually whitish in color, though 
sometimes brown. "It is plump and slightly broader than 
thick." In the union of the abdomen with the thorax the little 
pedicel or stem found in the ant is lacking, the abdomen being 
broad at the base. They are blind or have simple eyes. They 
conceal themselves from the light. The slender antennge look 
like strings of tiny beads. 

The young are all apparently alike when hatched, but by 

some means not understood they are afterward developed into 

soldiers, workers, males (kings), and females (queens). The 

winged males and females swarm, and each pair which is fortu- 

^ Damsel flies, Kellogg. 



132 



BRANCH ARTHROPODA 



nate enough to escape being eaten by birds finds a place for a nest, 
or is taken possession of by workers, and a new colony is founded. 
The males and females lose or divest themselves of their wings. 
Termites usually feed upon rotten wood, but some species 
attack soft plants and live wood, or even cloth, paper, and leather. 
In Africa these insects sometimes build pyramidal nests twenty 
feet high and form villages of them. They are so numerous 




Fig. 101. — White ant {Termes flavipes): a, Larva; b, winged male; c, 
worker; d, soldier; e, queen; /, pupa. (Riley.) 

and bold that ''nothing can defy the marauders but tin or 
iron."i Many species of insects have been found living a com- 
mensal life with termites, " a sort of insect economy termed 
termitophily." 

ORDER VI. ORTHOP'TERA 

This order comprises some of our most familiar insects, as 
the cockroaches, mantids, leaf-insects, walking sticks, short- 
horned grasshoppers (locusts), long-horned grasshoppers, and 
crickets. 

The Orthoptera usually have two pairs of wings. The 
anterior wings are thicker and overlap or cover the posterior 
wings when the insect is at rest. The walking-stick is wingless. 

1 Drummond. 



OETHOPTERA 133 

The grasshopper (see Fig. 85, p. 113) may be taken as typical of 
this order. 

The Head. — The mouth parts consist of a labrum or upper 
hp, the mandibles, a pair of crushing or biting jaws, followed 
by a pair of maxillce, or smaller jaws, each of which consists of 
three parts — an outer, jointed maxillary palpus, and a spoon- 
shaped piece which covers the brown incurved maxilla. Then 
follows the labium, or lower lip, with its jointed labial palpi. 
On the head are two compound eyes and three simple eyes, 
or ocelli, and a pair of antennae or feelers. 

The thorax is divided into three well-marked divisions: 
First, is the movable, cape-like prothorax, to which is attached 
the first pair of legs. Second, is the mesothorax, bearing the next 
pair of legs and the anterior pair of wings, which are straight 
and rather narrow. Third, is the metathorax, with the large 
third pair of legs and the posterior wings, which fold up like a 
fan under the anterior wings when not in use. 

The segmented abdomen follows the thorax. Close observa- 
tion with the magnifying glass will show minute openings on the 
sides of the segments. These openings are the spiracles or 
breathing pores. 

" Singing." — This order of insects gives us most of our 
" singers " and leapers of the insect world, and, strangely enough, 
the leapers are the singers, and, stranger still, they sing without 
a voice. Of the six families of Orthoptera, three are composed 
of these leaping and " singing " insects. The locust or short- 
horned grasshopper, when at rest, makes a noise by rasping the 
inner surface of the hind thighs across the thickened and ridged 
longitudinal vein of the outer surface of the fore wings. In the 
air, the " clacking " is made by rubbing the upper surface of the 
anterior margin of the hind wings back and forth past the 
under surface of the posterior margin of the fore wings. " This 
can be heard for a distance of several rods."^ 

The male cricket holds his fore wings (Fig. 102) up over his 
body and rubs together the upper side of their basal region. 
The male tree crickets, katy-dids, meadow-green grasshoppers 
with long antennae, also rub together specially modified por- 
tions of the fore wings. 

, 1 Kellogg, p. 134. 



134 



BRANCH ARTHROPODA 



Hearing.— The " ears " consist of a pair of small tympanic 
membranes, situated on the basal segment of the abdomen in 
the locust and on the tibiae of the forelegs (Fig. 95, p. 123) 
of the cricket and katy-did. Associated 
with each tympanum is a vesicle filled 
with liquid and an auditory ganglion, which 
is connected by a nerve with one of the 
thoracic ganglia. 

Feeding. — All Orthoptera have biting 
mouth parts, and bite off and chew their 
food. Most of them are vegetable feeders, 
but the mantis is carnivorous. The locusts 
or grasshoppers have at times wrought 
great havoc with man's crops, as both 
sacred and secular history tell us. 

Leaping. — In the leaping Orthoptera the 

posterior pair of legs is especially adapted 

for this purpose. They are large and long, 

and when walking the knee-joints are much 

higher than the insect, thus giving leverage for their prodigious 

leaps, in which they rival the fleas in their athletic records. 

The metamorphosis is incomplete, the young (nymphs) 
(Fig. 103) differing from the parents in size and absence of wings 
(Fig. 104). 




Fig. 102.— Wing 
of cricket musician 
(enlarged) , showing 
the file at a and the 
scraper at b. 




Fig. 103. — Calopt'enus spre'lus: a, a, Newly hatched larvaj; b, full-grown 
larva; c, pupa, natural size. (After Riley.) 



The cockroaches (Blat'tidoe) are nocturnal insects, found about the 
pantries and water-pipes of our dwellings, though in the North, according 
to Comstock, our native species lives in woods and fields. One may often 
find them hiding under bark, sticks, and stones. The jaws are strong and 
toothed, and they are greedy little creatures, devouring anything they can 
get, " eating book-bindings and bed-bugs with equal alacrity." The body 
is flat and slippery and the legs are adapted for rapid running, enabling 



ORTHOPTERA 



135 



them to escape readily into cracks and crevices. Cockroaches were the 
dominant msects m carboniferous times. There are four common species^ 




wif&s^;x;sr:tthi^ 




Fig. 105.-African mantis or soothsayer, with its egg-mass. (Monteiro.) 

only one being native to the United States. The eggs arc laid in simll 
bean-shaped, horny, brown cases. The young a?e precocial! Coci- 



136 



BRANCH ARTHROPODA 



roaches may be gotten rid of by dusting fresh insect-powder into the 
cracks of pantry and kitchen with a little hand-bellows. 

The praying mantids (Man'tidoe) (Fig. 105) are peculiar insects which get 
their name from the attitude in which they watch for their prey. They 
stand motionless with the head raised upon the long prothorax and the 
front legs clasped in front of the face. These front legs are spiny and are 
used only for seizing and holding their prey. The wings are usually leaf- 
like in color and texture, and this special protective resemblance is very 
good when the insect rests upon a plant. They are carnivorous and do 




Fig. 106.- 



-A walking-stick among the stems of a flower-cluster, 
life.) 



(From 



much good in destroying insect pests, so much indeed that Professor Slinger- 
land is trying to establish and distribute a European species in the United 
States. Most of the mantids — less than a score of species — are tropical. 
Our most common native species, Phasmoni'^tn'tis caroli'na, is about 2^ 
inches long. They are everywhere regarded with strange superstition, 
and the superstitious say one should " never kill a mantis, as it bears 
charm against evil." A Japanese mantis {Tinode'ra sinen'sis), recently 
introduced into the United States, is brown. This protection conceals 
the insect not only from its enemies, but from its prey, for which it " lies 



ORTHOPTERA 



137 



\; 



in wait," and may thus be called aggressive resemblance. Several species 
from India resemble flowers, and thus attract insects, upon which they 
feed. This is an example of alluring colors. 

The walking-sticks {Phas'midoB) (Fig. 106) afford even better examples 
of special protective resemblance than the mantids. Our species are 
wingless and may be either green or brown, and are usually found upon 
twigs of a color corresponding to that of their bodies. The body, which 
is long, straight, and slender, looks exactly like a twig, while the slender 
legs look like so many tiny branches. One may pick up a walking-stick, 
thinking it a twig until it moves. Although it is so repulsive to the unin- 
itiated, it is a perfectly harmless creature. The only common species in the 
northern states, Diapherom'era femora' ta, " feeds upon the leaves of oaks 
and other trees. It drops its hundred seed- 
like eggs loosely and singly on the ground, V 
where they lie through the winter, hatching \ 
irregularly through the following summer, "i 
01 even the second summer. Over six hun- 
dred species of this family are known. They 
are numerous in the tropical and sub-tropical 
countries and present many striking resem- 
blances to their environment, one of the most 
perfect of which is the " green-leaf insect " 
(Fig. 90, p. 117). Its wings, flat body, ex- 
panded legs, and even head and prothorax 
are bright green flecked with yellow, making 
it look wonderfully like a leaf attacked by 
fungi. 

" The locusts or short-horned grasshoppers 
(Acrid'idce) include those 'grasshoppers' in 
which the antennae are shorter than the body, 
and in which the ovipositor of the female is 
short and made up of four separate plates. "^ 
The tarsi have three joints. The first ab- 
dominal segment has a tympanic membrane 
on each side. It is to this family that the 
locusts mentioned in the Bible and in his- 
tory belong, as well as those which have 
wrought such havoc in our own country. 
A conspicuous species is the common red- 
legged locust, Melan'oplus fe'mur-ru'brum. 
There are about five hundred species of this 
family in the United States, but only three or 
four of them are migratory. These go in swarms, sometimes so dense 
as to obscure the sun as a great cloud, and when they alight they literally 
devour every green thing in that region. The largest, most injurious, and 
most numerous of these are the Rocky Mountain locusts {Melan'oplus 
spre'tus). Their permanent breeding-grounds are upon the western pla- 
teaus, from 2000 to 10,000 feet above sea level, and they cannot endin-e 
for successive generations the low, moist land of the Mississippi Valley. 
" These locusts show a tendency to become gregarious from the beginning 
of their life as nymphs. A recent method of fighting them is to cultivate 

1 Kellogg. 

2 Comstock. 



Fig. 107.— Carolina lo- 
cust killed by a fungus. 
(Bulletin No. 81, _ New 
Hampshire Experiment 
Station Insect Record, 
1900.) 



138 



BRANCH ARTHROPODA 



in a sweet solution a destructive fungous growth (Fig. 107) . A few members 
of the swarm are dipped in the solution and turned loose, spreading the 
disease.! Melan'oplus atlan'tis sometimes does much harm in New England. 
Locusts lay their eggs, numbering from 25 to 125, in oval masses, cov- 
ered with a glutinous substance. The female deposits them (Fig. 108) in 
the ground or in rotten wood, with her strong, horny ovipositor, or they 
may be laid on the surface of the ground among the grass and weeds. The 
eggs are usually laid in the fall and hatch in the spring, there being but the 
one new brood a year. The young resemble the parents in general, having 
biting mouth parts and long legs. They are paler and wingless. The 
wings appear as minute scale-like projections and grow larger with each of 
the five or six molts (Fig. 104) Strangely enough, the hind wings, which 
are always underneath the fore wings in the adult, lie outside during devel- 
opment. Birds are the best exterminator. The eggs may be plowed up 




Fig. 108. — Rocky Mountain locust: a, a, a, Female in different positions, 
ovipositing; h, egg-pod extracted from ground, with the end broken open; 
c, a few eggs lying loose on the ground ; d, e, show the earth partially removed 
to illustrate an egg-mass already in place and one being placed; /, shows 
where such a mass has been covered up. (After Riley.) 



in the fall, or when they hatch in the spring the young could be crushed by 
heavy rollers or burned by scattering straw over the ground and Ughting it.^ 
Locus'tidae. — This family includes crickets, katy-dids, and long-horned 
grasshoppers. Unfortunately, the common name of locust is applied only 
to members of the family of Acrididoe, and to the cicada of the order 
Hemipiera, but to none of the Locustidoe. The long-horned meadow-green 
grasshopper has the delicate antennse longer than the body, the tarsi 
four jointed, the ovipositor sword shaped, and the tympanum on the 
tibia (Fig. 95, p. 123) of the front leg. The males call their mates by 

1 Linville-Kelly, p. 15. 

2 Kellogg, p. 139. 



ORTHOPTERA 139 

rubbing together the specially modified wing covers. These grasshoppers 
abound in our meadows everywhere. If you would know how perfect is 
their protective resemblance, try to find one which you have seen on the 
wing, after it has alighted. Some species found in caves are wingless, 
colorless, and blind. Their antennae and hind legs are developed to a great 
length. 

The katy-dids, of which there are several genera, are rather large, usually 
green insects. They live upon trees and shrubs, feeding upon foliage and 
tender branches, though they sometimes eat animal food. Only the males 
tell us " Katy did " or " she didn't." They usually " sing " at night from 
July or August until frost. They are not gregarious. Their thin, finely 
veined wings are almost indistinguishable in the foliage. 

Closely allied to the katy-dids, but looking more like crickets, are the 
wingless grasshoppers, the cricket-hke grasshoppers, and shield-backed 




Fig. 109. — Mole cricket {Gryllotal'pa boria'lis). (Burmeister.) 

grasshoppers. They are dull colored and live under stones and rubbish 
or loose soil. 

The crickets, of which there are few species, have the wing covers flat 
and overlappmg'above, and bent sharply down at the edge of the body like 
a box cover. The antennae are long and the ovipositor is spear shaped. 
They include the mole crickets, true crickets, and tree crickets. 

Mole crickets (Fig. 109) are fitted for a burrowing life. The front tibiae 
are broadened and shaped somewhat like the feet of a mole. They feed 
upon the tender roots of plants, and sometimes injure potatoes (Fig! 110). 

The true crickets, our familiar black species, live in houses or fields. 
They usually feed upon plants, but some are predaceous. The eggs, laid 
in the fall, usually in the ground, hatch in summer. Only a few of the 
old crickets survive the winter. 



140 



BRANCH ARTHROPODA 



The_ tree crickets live in trees or on tall plants. The female " snowy 
tree cricket " does much damage by laying her eggs in grapevines or rasp- 




Fig. 110. — Potato injured by mole cricket. 



berry canes, causing them to die above the puncture. These canes should 
be cut and burned in winter or early spring before the eggs hatch. 



ORDER VII. HEMIPTERA 

This order contains some of our most common and destruc- 
tive insects, as the chinch-bug, the grape phyllox'era, the San 
Jose scale, the bed-bug (Fig. 111)., the louse, the squash bug, 
stink-bugs of various kinds, plant-lice (Aphid' idee) , and bark-lice 
(Cdc'cidce), which furnish dye-stuffs, as cochineal, stick-lac, from 
which we get shellac, and China wax. 

The Hemip'tera include some five thousand species in North 
America. All of these species agree in that the mouth parts 
are modified into a piercing and sucking beak. Their food, con- 
sequently, is the blood of men or of other animals or the juices 
of plants. The sucking beak consists of the labium, which, to- 



HEMIPTERA 



141 



gether with the labial palpi, is modified into a jointed sheath. 
This incloses the mandibles and maxillae, which are changed 
into long, piercing stylets.^ The labrum or upper lip is small or 
rudimentary. There are usually four wings. In the typical 
Hemiptera, as exemplified in the sub-order Heterop'tera, the 
character of the anterior wings is a distinguishing feature. 
The basal portions of these wings are thickened and parch- 
ment-like, while the terminal portions are membranous and 
overlap when the wings are folded over the back. From the 
character of these wings the order gets its name — hemi, half. 



"'-ic:^' 




'Fig. 111. — 'Red-hn^ {Ci'mexlectular'ius): a, Adult female gorged with 
blood; 5, same from below; c, rudimentary wing-pad; d, mouth parts. 
All enlarged. (Marlatt, Bull. U. S. Dept. of Agriculture, 1896.) "The 
characteristic odor of bugs is due to the secretions of certain stink glands, 
which in the young open on to the upper surface of the abdomen and in the 
adult open on each side of the metasternum." — Sedgwick. 

and pteron, a wing, i. e., the Hemip'tera or " half-winged " 
insect. The second pair of wings are membranous and fold un- 
der the fore wings when not in use. The electric-light bugs, 
bed-bugs, water-bugs, and squash-bugs are familiar examples. 
In the sub-order Homop'tera the anterior wings are not thick- 
ened, but are of the same structure throughout, as in the cicada. 
In the sub-order Parasl'ta are found wingless parasitic hemip- 
tera which prey upon certain mammals, for example, the head 
and body lice of man, dogs, cattle, hogs, sheep, mice, and 
rabbits. 

1 See Kellogg, p. 164. 



142 



BRANCH ARTHROPODA 



The giant water-bugs (Belostom'idce) are an example of the largest 
Heteroptera or true bugs. They are often seen about electric lights. They 
j0[y from pond to pond and are very rapacious, feeding upon the juices of 
young fishes, insects, and tadpoles. 

The chinch-bug family (Lygoe'idw) has nearly two hundred species in the 
United States. The most destructive is the small but widely distributed 
chinch-bug (Blis'sus leucop'terus) (Fig. 112), and though it measures less 
than ^ inch in length, it costs the United States $20,000,000 annually, for 
it is " the worst pest of corn and one of the worst of wheat." There are two 
generations of the chinch-bug annually. The adults winter under rubbish, 
and in early spring they lay their eggs in fields of grain upon roots or stems 
beneath the soil. They hatch in about two weeks, and the little red nymphs 
attack the root and then the stalk of the wheat. They mature in about 
six or seven weeks, when they are " blackish, with the wings semitransparent 
white, and with a conspicuous small triangular black dot near the middle 
of their outer margin." At about harvest time they migrate by the 




Fig. 112. — The chinch-bug {Blis'sus leucop'terus): a, b, Eggs; c, newly 
hatched larva; d, its tarsus; e, larva after first molt; /, same after second 
molt; g, pupa — the natural sizes indicated at sides; h, enlarged leg of per- 
fect bug; j, tarsus of same still more enlarged; i, proboscis or beak, en- 
larged. (Riley.) 



millions to fields of growing corn, marching in a body like an approaching 
army. When the bugs of the first brood have reached maturity, they pair, 
at which time only they use the wings, and the second generation is begun. 
The adults of the second generation that survive the winter lay the eggs 
for the spring brood. It is thought that a third brood sometimes appears 
in Kansas. 

Their migration from wheat to corn fields may be hindered by plowing 
furrows around the fields and pouring crude petroleum or coal-tar into these 
moats. If this has not been done, when the bugs collect on the first few 
rows of corn they should be sprayed at once with kerosene emulsion. 
Fredaceous insects, as the aphis-lion and ladybird beetles, and birds hold 
them in check. But a parasitic fungus (Sporotri'chum globulif'erum) 
will kill the bugs rapidly in moist, warm weather. 

The cicadas (Cicad'idce) are easy of recognition on account of their 
large, blunt-headed, robust bodies, the three ocelli, and their shrill " sing- 
ing " during the daytime in the late summer and early fall. The male 
does all the talking or singing, if you choose to call it a song, and " his wife 



HEMIPTERA 



143 



cannot talk back." The sound is made by " stretching and relaxing a pair 
of corrugated tympana or parchment-like membranes by means of a 
muscle attached to the center of each."^ 

The strangest freak in all insect life is the periodical cicada or seventeen- 
year locust (Fig. 113). It is the longest lived of all insects, for while 
other insects pass from the egg to imago form in a few days or weeks, or, at 
the most, in one to three years, this insect requires from thirteen to seven- 
teen years for this development. In the spring the female cuts slits in 
tender twigs and lays her eggs therein. In about six weeks they hatch 
and the nymphs spend the required seventeen years, or, in the case of a 
southern form, thirteen years, in the ground. They feed by sucking the 
juices of tender roots. In the spring of the seventeenth or the thirteenth 
year — as the case m.ay be — they crawl up to the surface of the ground, 




Fig. 113. — The seventeen-year Cicada (( 
eggs (e) ; /, larva. 



and pupa (a, h) ; d, position of 
(Riley.) 



undergo their last molting, and emerge as clear-winged cicadas. This 
insect is a fine example of protective resemblance. One may be within 
a few inches of a " singing " cicada and not be able to see it, so near the 
color of the tree trunk or ground is it. The adult life is short. They lay 
their eggs, sing their songs, and die. 

The plant-lice or aphids {Aphid'idce) are among our most common and 
destructive pests in the green-house, field, and orchard. There are many 
species, most of which are small, the largest barely reaching the length of 
i inch. The small, soft, usually green body is somewhat pear shaped. 
Wingless forms are most numerous, but there are forms in almost every 
brood which have two pairs of delicate transparent wings, the anterior 
pair of which is the larger. " The two wings of each side are usually con- 

1 Kellogg, p. 167. 



144 BRANCH ARTHROPODA 

nected with a compound hooklet."i The sucking beak is three jointed 
and may or may not be longer than the body. They have prominent com- 
pound eyes and usually ocelli. The long antennae are from three to seven 
jointed. Many species have on the sixth segment of the abdomen two 
tubular processes, long supposed to be the honey tubes, but Kellogg says 
" from them issues another secretion, not sweetish, about which little is 
known," and that the "honey-dew" so relished by ants (p. 179) "is 
now known to be an excretion from the intestine issuing in fine droplets 
or even spray from the anal opening." It is sometimes produced in large 
quantities, so that the leaves below the plant lice are coated with it and the 
walks beneath the trees spotted by it. It is fed upon by bees and wasps 
as well as by ants. In addition to the "honey-dew," many species secrete 
another fluid, which is excreted as a liquid through "various small open- 
ings scattered over the body." This liquid soon hardens into a wax. 
The total waxy secretion appears as a mass of felted threads or wool, as in 
the wooly apple aphis, and probably serves as a protection for the soft, 
defenseless body. 

The aphids are remarkably varfeble as regards their reproduction sexually 
or agamically,^ and as regards their possession of wings, so that the life- 
history varies not only in different species, but in the same species under 
different conditions. The eggs are laid in the fall, and from them hatches, 
in early spring, a colony of wingless individuals which may produce (without 
pairing) either living young or eggs. This may continue under favorable 
food supply and temperature for a number of generations. Slingerland, 
of Cornell University, reared four generations of wingless "agamic" 
aphids. At any time, especially if food becomes scarce or other conditions 
unfavorable, winged individuals are likely to appear and fly away to other 
host plants, where they produce, agamically, new colonies. If temperature 
becomes low or other unfavorable conditions occur, these asexual individuals 
produce a brood consisting of both males and females. " The males may 
be either winged or wingless, but the females are alv,^ays wingless." These 
sexual forms pair and produce one or more large fertilized eggs which lies 
dormant over winter and hatches into a wingless " stem-mother " in the 
spring, and a series of agamic generations follow. The multiplication of 
aphids is so rapid that, were it not for predaceous insects, such as lady- 
bird beetles, aphis-lions, and parasitic Hymenop'tera, and for insect-loving 
birds (see Birds), they would utterly destroy their host plant and ulti- 
mately starve themselves. Professor Forbes made an estimate of the rate 
of increase of the " corn-louse," and found that if " all the plant-lice de- 
scending from a single ' stem-mother ' were to live and reproduce through- 
out ithe year we should have coming from the egg the following spring 
9,500,000,000,000 young. As each plant-louse measures about 1.4 mm. 
in length and 0.93 mm. in width, an easy calculation shows that these 
possible descendants of a single female would, if closely placed end to end, 
form a procession 7,850,000 miles in length." 

Aphids vary greatly in their feeding habits, many feeding upon the 
juices of tender leaves, stems, leaf-buds, or blossom-buds, while others 
suck the juices of tender roots in the soil, and sometimes the same species 
lives both above and below ground. Above ground they may be fought 
by strong solutions of soap, by kerosene emulsion, or by a weak solution of 
nicotin. Since they suck the juices of plants they cannot be affected by 
poisoning the food. Underground, carbon bisulphid is sometimes used, 

1 Comstock. 2 Glossary. 



HEMIPTERA 



145 



but about the best remedy is to destroy the infested tree or vine, and plant 
one of another species which is not a host-plant for the pest. 



.-^=^1:^ .^^upcc 




Fig. 114. — Phylluxe'ra vastd'trix: a, Leaf with galls; h, section of gall 

showing mother louse at center with young clustered about; c, egg; d, 

larva; e, adult female; /, same from side, (a, Natural size; h-f, much 
enlarged) . (Marlatt . ) 




Fig_. 115.; — Phylloxe'ra vasta'trix: a, Root-galls; b, enlargement of same, show- 
ing disposition of Uce; c, root-gall louse, much enlarged. (Marlatt.) 



The grape Phylloxe'ra (Fig. 114) is a native aphid found upon the wild 
grapevines of the eastern United States. It was introduced into the 
south of France before 1863 upon rooted vines sent from America, and, 
10 



146 



BRANCH ARTHROPOD A 



curiously enough, says Kellogg, "came to California — in which state it has 
done much more damage than elsewhere in our country — from France, in- 
troduced upon imported cuttings or roots " (Fig. 115). Probably not less 
than 30,000 acres of vineyards have been destroyed by it since it was first 
noticed in 1S74. " The Phylloxera appears in four forms: (1) the gall 
form, living in little galls on the leaves (Fig. 114), and capable of very 
rapid multiplication (this form rarely appears in California); (2) the root 
form (Fig. 115), which is derived from individuals which migrate from 
the leaves to the roots, and wliich by the piercing of the roots, sucking the 
sap, and producing little quickly decaying tubercles on the rootlets, does 
the serious injury; (3) the winged form (Fig. 116), which flies to new vines 
and vineyards and starts new colonies; and, finallj^, (4) the sexual forms, 




Fig. 116. — Phylloxe'ra vasta'trix: a, Migrating stage, winged adult; b, 
pupa of same; c, mouth parts with thread-like sucking setae removed from 
sheath; d and e, eggs showing characteristic sculpturing; all enlarged 
(Marlatt.) 



male and female (Fig. 1171, which are the regenerating individuals, ap- 
pearing after several agamic generations have been produced." The gall 
stage may be omitted, and the individuals hatched from the fertilized eggs 
go directly to the roots. The gall form can be prevented by spraj'ing to 
kill the winter eggs. But about the onlv real cure for the infested roots is 
to dig them up and burn them and plant out resistant vines. The wild 
vines of the ^Mississippi Valley have evolved with the Phylloxera, and are 
capable of living and!^ growing in spite of the pests. The French vine- 
yards, as well as those of California, are being renewed by grafting French 
stocks upon the resistant roots, thus rendering the vines practically im- 
mune. There are manj- species of aphids, but this example must suffice for 
our present work. 

Scale-bugs, mealy-bugs, and others iCoc'cidcp) compose a very anomalous 



HEMIPTERA 



147 



group, the species differing greatly in appearance, habits, and metamor- 
phoses from those of the most closely allied families, and even the two sexes 




Fig. 117. — Phylloxe'ra vasta'trix: a, Sexed stage larviform female, the 
dark-colored area indicating the single egg; b, egg, showing the indistinct 
hexagonal sculpturing; c, shriveled female after oviposition; d, foot of 
same; e, rudimentary and functionless mouth parts. (Marlatt.) 




Fig. 118. — Ladybird feeding on scale insects, Pentil'ia (Stnilia) miseVla: 
a, beetle; b, larva; c, pupa; d, blossom end of pear, showing scales with 
larvae and pupae of Pentilia feeding on them, and pupae of Pentilia attached 
within the calyx; all enlarged. (Howard and Marlatt, Bull. U. S. Dept. 
of Agriculture.) 



of the same species, says Comstock, differ greatlj\ The males, unlike all 
other members of the order, undergo a complete metamorphosis. The adult 



148 BRANCH ARTHROPODA 

male has but a single pair of wings and has no organs for procuring food. 
The mouth parts disappear during metamorphosis and a second pair of 
eyes develops. The adult female is always wingless and the body is always 
scale-like or gall-like in form, or grub-like and clothed with wax. Those 
of some species retain their eyes, antennae, and legs, while others are fixed 
in adult life and very degenerate, lacking eyes, antennae, wings, and legs. 
In speaking of the San Jose scale, Kellogg says, ' ' it has a long, fine, flexible 
process projecting from near the center of its under side, this is its sucking 
proboscis, and serves as a means of attachment as well as an organ of feed- 
ing." The San Jose scale is very prolific. It was ascertained at Washington 
that there are four regularly developed generations and possibly part of a 
fifth in a year. It is estimated that about 200 females (and about the same 
number of males) are given birth to by each female. Thus the descendants 
of a female amount to 3,216,080,400 individuals. From this it can easily 
be seen how destructive to fruit trees this pest soon becomes. It is now 
found in every state and territory and in Canada. Many states have 
laws to try to prevent its distribution with nursery stock. 

Perhaps the most effective remedy is the fumigation of orchard trees by 
hydrocyanic gas. To do this the tree is entirely enclosed in a large tent 
and the gas generated under it " by pouring about 50 ounces of water into 
5 ounces of commercial sulphuric acid and dropping into it 15 ounces of 
cyanid of potassium." These amounts are sufficient for a tree 12 feet high 
with a spread of 10 feet. The fumes are deadly poison. Of sprays for 
leaves and greenhouse plants, crude petroleum and kerosene emulsion are 
best. Protection of the birds is one great means of holding these pests in 
check. It has been proved by the examination of 226 stomachs that more 
than one-fifth of the food of the blackheaded grosbeak {Zamelo'dia melano- 
ceph'ala^) consists of scale insects. For the work (Fig. 118) of ladybird 
beetles see p. 147. 

ORDER VIII. COLEOP'tERA 

This order consists of eleven or twelve thousand species in 
America, north of Mexico. 

The mouth parts of beetles (Fig. 119) consist of the upper 
lip or labrum, the jaws or mandibles for seizing the prey or for 
gnawing; the complicated many pieced maxillce with usually 
prominent maxillary palpi; the lower lip or labium of several 
parts, and rather large labial palpi. These mouth parts are 
adapted for biting, and are not easy for beginners to identify. 
The student should identify these parts on a large beetle with 
the help of a good figure (Fig. 119) and a good magnifying 
glass. 

Compound eyes are present, but usually the simple eyes are 
wanting. 

The wings are four in number, except in some ground beetles, 
which have only the anterior pair. The anterior wings are 
1 Plate III, Bulletin 32, U. S. Biological Survey. 



COLEOPTERA 



149 



quite rigid and meet in a line on the back, forming a sheath to 
inclose the membranous posterior wings, which fold up under 
the fore wings or elytra when not in use. 

The body is usually compact. The under surface of the 
abdomen is hard, but the upper surface beneath the elytra is 
soft and yielding, thus permitting respiration. 




Fig. 119. — Under surface of Har'palus caligin'osus: a, Ligula; b, para- 
glossa; c, supports of labial palpi; d, labial palpus; e, mentum; /, inner lobe 
of maxilla; g, outer lobe of maxilla; h, maxillary palpus; i, mandible; k, 
buccal opening; I, gula or throat; m, m, buccal sutures; n, gular suture; 
o, prosternum; p', episternum of prothorax; p, epimeron of prothorax; 
q, q', q", coxae; r, r', r", trochanters; s, s', s", femora or thighs; t, t', t", 
tibiae; v, v^, v^, etc., ventral abdominal segments; w, episterna of mesothorax 
(the epimeron is just behind it); x, mesosternum; y, episterna of meta- 
thorax; y', epimeron of metathorax; z, metasternum. (After Leconte.) 



The Young. — The metamorphosis is complete. The larvae 
are usually called grubs. (See Fig. 120, p. 150.) Their habitats 
vary much. Some live in trees, others, as the larvae of the tiger 
beetle, burrow in the gound, and, with the head at the sur- 
face, watch for their prey. Their food varies according to the 



150 



BRANCH ARTHROPODA 



habitat. The burying beetles (Fig. 120) (Necroph'orus) pro- 
vide food for their young by burying carrion, as a dead mouse or 
bird. When it is covered over with earth the female lays her 
eggs upon the carcass. They soon hatch and the larvae feed 
upon the food thus provided for them. 

The food of the adult Coleop'tera also varies much. Some, 
as the ground beetles (Carah'idce), are predaceous. Others, as 
the carrion beetles, feed upon decaying animal matter, while 




Fig. 120. — Necroph'orus burying a mouse, and larva. (Landois.) 



others, as the Colorado potato beetles, are voracious plant 
feeders, making this order of much economic importance. 

Other familiar examples are the apple-tree borers, the 
wire-worms, fruit and grain weevils, and the white grubs of the 
June beetles (Fig. 121). 

The tiger beetles {Cicindel'idce) are usually of a beautiful metallic green 
or bronze, banded or spotted with yellow, though some are black, while 
those living in white sand are exactly the color of the sand. They are 
the most active of all beetles, running and flying well. They may be 
found on bright warm days on dusty roads or along the banks of streams. 



COLEOPTERA 



151 



Comstock says they remain still until within our sight, but out of reach, 
and then " like a flash they fly up and away, alighting several rods ahead 
of us," with eyes toward us. The ugly larvae live in vertical burrows 
about a foot deep on beaten paths or in the sand. The larva, with its dirt- 
colored head which is bent at right angles to its lighter colored body, plugs 
the entrance to its burrow, and with its wide-open jaws forms a living 
trap for passing insects. On the fifth abdominal segment there is a hump 
bearing two hooks curved forward, by which the larva holds fast, thus pre- 
venting large prey from dragging it out of its burrow. 

The ground beetles (Fig. 122) (Carab'idoe) are probably the most im- 
portant family of predaceous insects, though a few species are vegetable 
feeders. They are usually dark colored and nocturnal, but some are large 
and brilliantly colored, and the wing covers are generally " ornamented 
with longitudinal ridges and rows of punctures." They hide in daytime 
under stones and logs. There are about twelve hundred species in North 




Fig. 121.— June beetles: 1, Pupa; 2, larva; 3, 4, adult. (Riley, Report of 
State Entomologist of Missouri.) 

America. The larvae of most of them are long flattened grubs, with body of 
uniform breadth throughout, protected on top by horny plates, ending in a 
pair of conical bristly appendages. Usually they bury themselves just 
beneath the surface and feed upon insect,s which ent^r the ground to 
pupate. They destroy large numbers of leaf-feeding beetles or their 
larvffi. They pupate in small round cells in the soil, from which the adults 
push their way out. 

The caterpillar hunter {Caloso'ma scruta'tor) is a familiar example of the 
ground beetles (Fig. 122). Its wing covers or elytra are bright green or 
violet, margined with reddish. It is found on trees at dusk. It is known to 
climb trees and make raids upon the hairy tent caterpillar, hence it is a 
friend. Two others {Calosoma Jrigidum and C. calidum) are hunters of cut- 
worms and canker-worms. The latter is sometimes called the fiery hunter, 
from the rows of reddish pits on its black elytra. 

Another one {Agonod'erus pal'lipes) feeds upon sprouting corn, 



152 



BRANCH ARTHROPODA 



The carnivorous water beetles (Dytic'idce), of which there are three 
hundred species, are found everywhere in streams and ponds (Fig. 123). 
They vary in length from i to 1^ inches. The diving beetle projects the tip 




Fig. 122. — Ground beetle (Calosoma), similar to C. scrutator; below, a 
Carabus. (Brehm.) 

of its abdomen through the surface film to breathe. It raises the elytra a 
little, and the air which is caught under them is held by the fine hairs on the 




Fig. 123. — Carnivorous water beetles. (Brehm.) 

back, where the spiracles are situated. Thus, it carries a supply of air 
which enables it to breathe under water. These beetles make interesting 
aquarium specimens. 



DIPTERA 153 

Platypsyl'la casto'ris is the sole representative of the family Platypsyl'lidce. 
This queerly shaped beetle lives a parasitic life upon beavers. It is wingless 
and blind, and the elytra are rudimentary and short, exposing five abdomi- 
nal segments. Its degeneration is due to its parasitic life. 

The lady-bugs {Coccinel'lidce) are interesting little predaceous beetles, 
yellow or reddish, with black spots. The cottony cushion-scale {Ice'rya 
purchasi), so destructive to California fruits, was subdued by a lady-bug 
{Veddlia cardindlis) brought from Australia to feed upon it. The hop 
louse is destroyed by the larvae of certain lady-bugs known as " niggers." 
The lady-bugs, with few exceptions, are predaceous. One {Epilach'na 
borea'lis) is herbivorous. Its larva, which is yellow and clothed with 
forked spines, feeds upon the leaves of the squash farnily. 

The little carpet beetle {Anthre'nus scrophula'rioe) is a household pest. 
Its larva feeds upon carpets, furs, feathers, and woolens. 

The fireflies (Lampyr'idce) or " lightning-bugs " are not flies, but beetles. 
The light giving has never been fully explained. " The light-giving organ 
is usually situated just inside of the ventral wall of the last segments of the 
abdomen, and consists of a special mass of adipose tissue richly supplied 
with air-tubes (tracheae) and nerves. From a stimulus conveyed by these 
special nerves oxygen, brought by the network of tracheae, is released, to 
unite with some substance of the adipose tissue, a slow combustion _ thus 
taking place. To this the light is due, and the relation of the intensity or 
the amount of light to the amount of matter used up to produce it is the 
most nearly perfect known to physicists. "^ 

Mynnecoph'ilous Beetles. — There are nearly one thousand species 
of beetles which live in the nests of ants. Many of them are conimensal 
with the ants, deriving perhaps the greater benefit by the association, but 
others live truly symbiotically with their hosts. ^ They secrete a sweet 
substance which is eaten by the ants, which in return shelter, clean, and, 
by regurgitation, feed them. They are strangely modified for this mode 
of life, usually by degeneration. 



ORDER IX. DIP'tERA 

This order contains about fifty thousand species, of which 
about seven thousand are known in America. It includes some 
famous flies (Fig. 124). 

The mouth parts are adapted for piercing and sucking or for 
lapping. Just what constitutes these mouth parts is a contro- 
verted question among scientists. Comstock says, ''According 
to the most generally accepted view the six bristles represent 
the upper lip {labrum), the tongue (hypopharynx) , the two 
mandibles, and the two maxillae, and the sheath enclosing these 
bristles is the lower lip (labium).'^ Identify these parts on the 
head of a big fly with the aid of a large figure and a magnifying 
glass. 

1 Kellogg, p. 269. ^ Kellogg, p. 553. 



154 



BRANCH ARTHROPODA 



The Wings. — As the ordinal name indicates, these insects 
have two membranous wings. No fly has more than two 
wings and only a few are wingless. They have, however, 
vestiges of a second pair, called halte'res or balancers, ending in 
short knobs. They are used in directing the flight and are be- 
lieved by some to be auditory organs. 

Family Mus'cidae. — The common house-fly {Mus'ca domes' tica) is too well 
known for our comfort. It hibernates. One will recall having seen flies 
about the house during the winter. They breed about stables in the sum- 




Fig. 124. — Typhoid fever or house-fly {Mus'ca domes' tica): a, Adult male; 
h, proboscis and palpus of same; c, terminal joints of antennae; d, head of 
female; e, puparium; /, anterior spiracle; all enlarged. (Howard and 
Marlatt, Bull. U. S. Dept. of Agriculture, 1896.) 



mer. The eggs, numbering about one hundred, hatch in about twenty- 
four hours. The soft, white, cyhndric, footless larva is called a maggot. 
It feeds and grows for about a week, molting twice, and then pupates 
within the larval skin, or puparium, for another week. It then makes a 
circular opening in the puparium and emerges as the^ adult fly, thus giving 
time for a number of generations. In a summer the offspring of a single 
fly may reach incredible numbers. It is now known that the principal in- 
sect agent in the spread of typhoid fever is the common house-fly, and 
great care should be taken to prevent its breeding. All human and horse 
excreta should be kept in fly-tight vaults and sprinkled with chlorid of 
lime or quick lime at least once a week, unless wanted for fertilizing 
purposes. All garbage cans and swill pails should be kept covered, and 



DIPTERA 



155 



sprinkled with lime when emptied. Chicken pens should be cleaned often 
and sprinkled with lime. 

The many little projections on the feet of the fly are tubular, and secrete 
a sticky fluid which enables it to walk upside down. 

The blow-fly and the flesh-fly, close relatives of the house-fly, lay their 
eggs upon meat, cheese, and other provisions or upon decaying animal sub- 




Fig. 125. — An adult mosquito, much enlarged, with all the parts that are 
used in classification named. (Smith, N. J. Experiment Station, Bulletin 
171, 1904.) 

stance, on which the maggots feed. Thus, while a great annoyance, they 
may do some good by acting as scavengers. The most common flesh-fly 
is perhaps Sarcoph'aga sarrace'nioe, which resembles a large house-fly. It 
furnishes another example of viviparous insects; in other words, the larvse 
are brought forth alive. 



156 



BRANCH ARTHROPODA 



Horse-flies (Taban'idce) are also pests of man and beast. They are 
most abundant in the hot summer days. The large black-bodied horse- 
flies, of which there are a hundred species, belong to the genus Tabanus. 

The Bot-flies {(E'stridoe). — " The horse bot-fly {Gastruph'ilus e'qui) closely 
resembles the honey-bee in form, except that the female has an elongated 
abdomen curved under the body." Horses have an instinctive fear of this 
fly. It attaches its eggs to the hair of the legs and shoulders of the horse, 
and they are taken into the mouth by biting the irritated place. The 
larvse fasten themselves to the lining of the stomach. When grown, during 
the fall and winter, they pass out and develop within a puparium. 

The larvse of Bot-flies of cattle or oxwarbles (Hypoder'ma linea'ta) live 
just beneath the skin on the backs of cattle, which are made frantic by their 
burrowing. 

The sheep bot-fly deposits its larvae in the nostrils of sheep, antelope, etc. 
They work up into the frontal sinuses and horns and cause the " staggers."^ 

Reindeer, deer, rabbits, and squirrels are infested by larvse of species of 
bot-flies, and one or two species infest man. 




Fig. 126. — 1, Egg-mass of the common mosquito; 2, larva breathing 
at the surface of the water; 3, a pupal mosquito. (From Hampton 
Leaflet.) 



Mosquitoes {Culic'idce) (Fig. 125) seem too well known to need descrip- 
tion, but there are other insects so similar that they are often mistaken for 
them. Comstock says ". the most distinctive feature of mosquitoes is the 
fringe of scale-like hair on the margin of the wing and also on all known 
American forms on each of the wing veins." The males differ from the females 
in having feathery antennae and in the absence of the piercing stylets . As 
a rule they do not sing or bite, and probably feed upon the juices of plants, 
as do the females if they cannot " get blood." The larvae (Fig. 126), called 
" wrigglers " or " wiggle-tails," are too often found near our dwellings in 
rain-barrels, slop-pails, open cisterns, open sewers, water troughs, lily-tubs, 
ponds, anywhere where the water is allowed to remain long enough for their 
development, which requires from eight to eighteen days. Of the three 
principal genera, Culex contains most of our mosquitoes whose bite and song 
are well known. Anoph'eles is the genus which is the intermediate host 
and the transmitter of the malaria germ. Of course it cannot transmit 

1 Comstock, p. 478; Hertwig, p. 493. 



DIPTERA 



157 



these germs unless it has been infected with them itself. Stegom'yia 

Jascia ta {b\g. 127) is the yellow-fever-carrying species, so much dreaded in 

our southern states. It has been 

established by observation and ex- 

perimenti that these mosquitoes, if 

they have bitten persons affected by 

malaria or yellow fever, actually 

carry these diseases, also that Steg- 

omyia fascia' ta and Cu'lex fati'gans, 

var. skusii, and Anoph'eles rossii 

carry certain forms of filariasis. 

These organisms belong to the 

round worms or Nematoda (see 

p. 41). The most common form of 

filariasis is elephantiasis. In this 

disease the legs and arms are af- 
fected. One leg may become so 

enlarged as to weigh as much as 
the rest of the body, or the arm 
may become a foot thick and horri- 
bly repulsive. In Samoa, says Kel- 
logg, fully one-third of the natives 
are attacked by this incurable dis- 
ease, which, though slow and almost 
painless, is certainly fatal. Ma- 
laria, so widespread in the United 
States, becomes even more prevalent and more often fatal in the tropics. 
Millions die from it every year. In a single year five million persons died 
^L .t f '^.^"^^^ ^lon^-^ Hence the mosquito is to be classed not sim- 
ply as a great annoyance, but as an insidious foe to health and life 




Fig. 127. — Stegom'yia fasci'ata (en- 
larged). (Howard, Bull. U. S. Dept. 
of Agriculture, 1902.) 




mo^m'iitn .V73« fV °'' harmless Fig. 129.-The malarial mosquito 

tTcTni horit^ f 1 ' T^ ^"^ ^7^''- '*^"^^ ^ith its head pointing down- 
H.rinf2 T fl*f\''''^^''^- (^'^^ ^a^d ^t an angle of from 20 to 30 
Hampton Leaflet.) degrees from a vertical or horizontal 

surface. (From Hampton Leaflet.) 

rr. S ''^"^™?" mosquito-. <^"^^-^ (Fig. 128), maybe distinguished from the 
malaria-carrying form (Fig. 129) in several ways. The female Culex has 

1 Kellogg, pp. 617, 630. 



158 



BRANCH ARTHROPODA 



short palpi, while the Anoph'eles has palpi nearly as long as the beak, making 
three long projections on the head. It may be distinguished also by the 
way it alights. The Culex is " hump-backed " with the beak pointing down- 
ward, while in the Anopheles the body and beak lie in the same plane. The 
eggs of Culex are laid in a boat-shaped mass, while the eggs of Anopheles 
are laid " singly and at random," but run together, forming irregular groups 
or strings. The larva of Culex hangs with the head down, so as to keep the 
end of the respiratory tube, which is borne by the next to the last somite, in 
contact with the air. The larval stage lasts about five or six days or longer 
in unfavorable conditions. The larva of Anopheles has a very short respi- 




Fig. 130. — A fine breeding-place for mosquitoes. (Hampton Leaflet.) 

ratory tube, and consequently lies in a horizontal position just under the 
surface film in order to obtain air. (This explains how it is that kerosene 
oil " poured upon the troubled waters " destroys the larvae. They are 
simply drowned or suffocated as the surface film of oil excludes the air.) 
The larval stage lasts from twelve to fourteen days. 

The mosquito larva, after growing several days and molting twice, changes 
into a club-shaped pupa (Fig. 126), the head and thorax being greatly en- 
larged, while the abdomen is slender. At the caudal end is a pair of leaf- 
like locomotor or swimming appendages. It takes no food, and when un- 
disturbed it floats upon the water, but when disturbed it is active, thus differ- 



DIPTERA 



159 



ing from the pupal stage of most insects. The pupa of Anopheles has a 
narrower and more pointed head and much shorter and wider breathing 
tubes than those of Culex. 

Mosquitoes flourish alike in the heated moist regions of the tropics and 
in the frigid regions of ice and snow. Many species have their haunts and 
breeding -places in fresh water, others breed abundantly and some perhaps 
exclusively in brackish water. They are found even in arid regions far 
from water, where it is probable they lay their eggs in the ground. So, 
go where we will, we cannot escape them, we must fight them. 




Fig. 131. — Wheat plant, showing injuries by Hessian fly: a, Egg of Hes- 
sian fly; b, larva; c, flaxseed; d, pupa or chrysalis; e, female, natural size; 
/, female; g, male; h, flaxseed or pupal stage between the leaves and stalk; 
i, chalcidid parasite; all enlarged except wheat stem and e. (After Riley, 
Burgess, and Trouvelot.) 



A very easy and successful way of getting rid of mosquitoes ina pond 
which will sustain fish is to stock it with such fish as the " top-minnow," 
sun-fish, and stickleback, whose young especially feed upon the larvae. 
Dragon-flies also should be encouraged and protected, since their nymphs 
feed upon the larvae of mosquitoes, and the adults are voracious feeders 
upon the mosquitoes. In fact, if it were not for the dragon-flies, life in the 
Hawaian Islands would be almost intolerable on account of the hordes of 
mosquitoes. Pools and marshes should be drained, or, if the pool or mud- 



160 



BRANCH ARTHROPODA 



puddle is small, it may be filled up with less expense. If neither can be 
done, then spraying with kerosene along the edges of the banks and the 
surface of the water every two or three weeks should be resorted to. The 
oil kills by contact many adults and larvae among the grass and weeds, and 
by coating the surface of the water with a film of oil the " wiggle-tails " 
are suffocated. Many females also are killed by this film of oil when they 
return to the surface to deposit their eggs. All open barrels (Fig. 130) 
and cisterns should be screened, so that the female mosquito cannot get to 
the water to deposit her eggs. 

The gall-gnats (Cecidomiji'idoe) are the smallest flies, but their great num- 
bers and their gall-forming habits make them great enemies of plants. 
There are about a hundred species in the United States, most of which are 



'DlPTEF^fK- 



■jHVMENOPfERfl,- 





voLuceLtfl. iNANS. 



Vespa Vulgaris, 





VoLi' Bomb '/lai4s> 



BoMQUs LapivariJs. 



Fig. 132. — Two cases of mimicry: flies resembling a wasp in the one, and a 
bee in the other. (Romanes.) 



destructive to cultivated plants. The minute reddish or white eggs are 
deposited on or in living plants, and the maggot-like larvae probably imbibe 
their food through the skin. 

The Hessian fly belongs to this family. It is a tiny blackish midge which 
lays its eggs (Fig. 131) in the sheaths of leaves some distance from the 
ground. The larva lives between the base of the leaf and the main stalk 
and feeds upon the sap of the growing wheat. There are four or five broods 
a year, both spring and winter wheat being infested. It is estimated that 
the ravages of this insect cost the farmers of this country $10,000,000 
annually. Were it not for its natural enemies, a half-dozen hymenop- 
terous parasites, it would soon take the whole crop of wheat, rye, and 
barley. The chief remedies which the farmer can use are the late planting 



SIPHONAPTERA 161 

of winter wheat ; the burning or plowing of stubble ; the early planting of 
strips of decoy wheat to attract the egg-laying females to deposit their eggs, 
and then to be burned; and the rotation of crops. ^ 

Another common and conspicuous gall-gnat is the pine-cone-willow gall- 
gnat, which lays its eggs in the newly formed buds of the willow. The 
stem ceases to grow, but the leaves continue, causing the bud to resemble a 
pine-cone. In this the larva remains through the summer and winter, 
pupating in early spring, soon after which the adult emerges. There are a 
number of others, as the clover-leaf midge, the clover-seed midge, and the 
wheat midge, each injurious to its respective crop. 

The Syrphus flies (Syr'phidw), of which there are twenty-five hundred 
species, differ much. Some species in the adult form imitate bees and 
wasps (Fig. 132). They can be distinguished by the longitudinal "spu- 
rious" vein between veins three and five. Some of the larvae are found in 
ants' nests and some in the nests of bumble-bees and wasps. One of the 
commonest is the yellow-banded species of the genus Syrphus, whose larvae 
do great good by destroying aphids, in whose colonies they live. 

The larvae of one of the bee-flies {Bombyli'idce) are also friends of man. 
They destroy many grasshoppers by burrowing into the egg-cases and 
devouring the eggs. The adults of these maggot-like larvae are swift, 
hairy, and bee-like, mimicking the bee in appearance and feeding habits. 

ORDER X. SIPHONAP'TERA 

The fleas consist of a single family, the PuUcidce, of nearly 
one hundred and fifty species, about fifty of which are found in 
the United States. Until recently the fleas were regarded as 
degenerate wingless Diptera, but entomologists now place 
them in a separate order. They are found usually as temporary 
external parasites on the cat, rat, rabbit, dog, poultry, and 
man. 

The mouth parts are adapted for piercing and sucking. 

They are almost wingless, the wings being represented by mere 

scaly plates. The bodies are naked, smooth, hard, oval, and 

compressed. The metamorphosis is complete (Fig. 133). 

The " small, slender, white, footless, worm-like grubs " are 

composed of thirteen segments. They seem to live on dry dust 

and the organic matter it contains. When grown they usually 

spin a silken cocoon and pupate in the dust. In the species 

infesting cats and dogs the larval life lasts only about a week. 

The development from the egg to the adult requires but two 

weeks. Fresh pyrethrum dusted about the rugs where dogs 

and cats lie, or spraying the rugs with formalin, will help get 

rid of fleas. 

1 Jackson and Daughterty's " Agriculture through the Laboratory and 
School Garden." 

11 



162 



BRANCH ARTHROPO-DA 



The chig'oe, a small flea of the West Indies and of South America, often 
causes serious trouble by burrowing under the toe-nail or the skin of the foot 
of man. The female burrows under the skin, becomes encysted and dis- 
tended by the eggs which hatch here, and unless the young are carried out 
by the pus they probably develop here. 




Fig. 133. — Common cat and dog flea (Pu'lex serrdt'iceps) : a, Eggs; h, 
larva in cocoon; c, pupa; d, adult; e, mouth parts of same from side; /, 
labium of same from below; g, antenna of same; all much enlarged. (How- 
ard, Bull. U. S. Dept. of Agriculture, 1896.) 

Rat Fleas. — It is believed that in tropical countries the disease germs 
of the bubonic plague may be transmitted from rats to men by the bites or 
punctures of rat fleas. 



ORDER XI. LEPIDOP'TERA 

This order includes such common insects as butterflies and 
moths or " millers." There are more than 6600 species in 
North America. 

The head is rather small for the size of the body. 

The mouth parts are highly complex, a striking example of 
adaptation of structure to function. The two maxillae are greatly 
modified into a long hollow tube (Fig. 141) for sucking the juices 
of fruits or the nectar of flowers. When not in use this tube, 
tongue, or proboscis is coiled up between two projections, the 
labial palpi. Many moths do not feed in the adult stage and 
the maxillae are lacking. The other mouth parts are mere 



LEPIDOPTERA 163 

rudiments. Find these rudiments on a large specimen and 
compare with the mouth parts of the grasshopper. 

The compound eyes are large and conspicuous. 

Some of the Lepidoptera have ocelli,^ one on either side above 
and near the margin of these compound eyes, but they are usually 
hidden by the scales covering the head. 

The many jointed antennae are very various in size, shape, and 
color. 

The thorax bears three pairs of legs and two pairs of wings. 
The wings are large, membranous, and covered with overlapping 
scales, which are, in reality, modified hairs. These scales 
strengthen the wings and give coloration to the species. 

The abdomen has no paired appendages. 

The metamorphosis is complete. The larvae of Lepidoptera 
are commonly called caterpillars. They are very destructive, 
being almost without exception injurious to vegetation. Com- 
stock says, "a very few feed upon plants below the surface of 
the water." The species which destroys scale-bugs, also those 
attacking woolen cloth, feed upon animal matter. Caterpillars 
are usually cylindric. The thorax bears six clawed, jointed, 
tapering legs, which develop into the legs of the adult. The ab- 
domen bears from two to ten thick, fleshy, non-jointed, contrac- 
tile pro-legs (see figure of silkworm, p. 126), which are shed at 
the last molt. The pro-legs are usually surrounded at the ex- 
tremity by many minute hooks. The mouth parts of caterpil- 
lars are formed for biting, hence they can be exterminated by 
the arsenical poisons when it is safe to use them. 

The Lepidoptera pupate in chrysalids or cocoons. The 
adult stage is the familiar winged form. It does no harm except 
the occasional puncturing of fruit to get the juice. 

Distinctions Between Butterflies and Moths.— The antennae of 
butterflies are fihform or thread-like for most of their length, but 
the end is thickened into a spindle-shaped enlargement or club. 
The antennae of moths are of various forms, usually filiform or 
pectinate (feathery), but never clubbed. Butterflies are diurnal, 
while the moths are crepuscular or nocturnal. Butterflies 
at rest fold the wings together in a vertical position above the 
back. Moths spread the wings horizontally, or fold them leaf- 
iComstock, p. 199. 



164 BRANCH ARTHROPODA 

like, or wrap them about the body, but never hold them in a 
vertical position. 

The skipper butterflies are diurnal, but, unlike other butter- 
flies, the antennae are usually recurved, forming hooks. Their 
bodies are more robust than those of other butterflies. They 
fold the wings, sometimes only the front ones, vertically when 
at rest. The skipper caterpillars are distinguished from other 
caterpillars by the unusually large head and the much constricted 
neck. Skippers spin thin cocoons of silk in which to pupate. 

Authorities enumerate 650 species of butterflies in the United 
States east of the Mississippi River. Kellogg gives six families of 
butterflies and forty-four of moths. Of the thousands of species 
with their various and interesting habits only a few can be 
mentioned. These should serve to stimulate the student to 
observe and study others. See " Laboratory and Field Guide " 
for collecting, breeding, and mounting. 

The carpenter moths {Cos'sidce), of which there are twenty species in North 
America, are, in the larval stage, wood-borers, burrowing about in the heart- 
wood of shade and fruit trees. Pepper and salt gray moths, indistinctly or, 
in a few cases, conspicuously marked with black and white, lay their eggs 
on the bark of trees, where the naked, grub-like larvse burrow into the wood. 
Here they tunnel through the wood for two to four years, according to the 
species. In this tunnel the pupal stage is spent. When ready for the adult 
stage the pupa works its way, by backward projecting saw-like teeth on the 
abdomen, to the opening of the tunnel, from which the moth emerges. 
The empty pupa skins may often be found projecting from the deserted 
burrows. 

The meal moth (Pyr'alis farina'lis), whose larva feeds upon meal, flour, 
or old clover-hay, is a common species. It is usually found near the larva 
food, but sometimes sits upon the ceiling with its tail curved over its back. 
Its expanse of wing is about an inch. The wings are light brown with red- 
dish reflections and a few wavy transverse lines. The larva makes long 
tubes of silk in the meal. Perhaps the most formidable mill pest is the 
Mediterranean flour moth {EpMs'tia kuehniel'la) . The caterpillars spin 
silken galleries through which they pass, making the flour lumpy and stringy. 

The coccid-eating pyralid {Loetil'ia coccidiv'ora) differs from other 
members of its family in being predaceous. It feeds upon the eggs and 
young of several scale insects. The larva spins a silken tube or bag, in 
which it lives. 

The codling moth (Carpocap'sa pomonel'la) (Fig. 134) is one of the best- 
known and most cordially hated of moths. It causes an annual loss in the 
United States of $10,000,000. The adult is small, with finely mottled, ash- 
gray or rosy fore wings. Near the square ends of these wings is a large brown- 
ish spot marked with metallic, bronze bands. The hind wings and abdomen 
are a lustrous light yellowish brown. This moth lays its eggs singly in the 
blossom end of an apple, just when the petals fall. When the larva hatches 



LEPIDOPTERA 



165 



it eats its way into the cere. The affected fruit usually falls to the ground 
before ripening. The full-grown larva burrows out of the apple and 
pupates in a cocoon under the rough bark of a tree. After two weeks in the 
pupal stage the adult of the first brood emerges and lays its eggs on later 
apples. The larvae are carried into the cellar with the fall and winter ap- 
ples, pupate in the crevices of the barrels or boxes, and remain till the fol- 
lowing apple-blossom time. Spraying the fruit with Paris green soon after 
the petals fall and again in about two weeks will greatly reduce the loss. 
At this time the fruit stands with the blossom end up and the poison will 
then reach the place where the larva hatches. "'^ The larva does not remain 
long in the apple after it falls to the ground. Hence if the apples are burned 
or fed to hogs at once the larvae will be destroyed. 




Fig. 134. — The codling moth: a, Apple showing burrow; b, place where 
the worm entered; d, chrysalis or pupa; e, larva or worm; /, moth with 
wings closed; g, moth with wings spread; h, head end of larva; i, cocoon 
in which the larva changes to a chrysalis. All about life size except h. 
(Riley.) 



The geometrids are of interest because of the peculiar phase of protec- 
tive resemblance possessed by their larvae. They cling by their posterior 
legs to the branches of trees or other plants, and, holding the body out 
straight, stiff, and still, look, for all the world, like short, stubby branches. 
My little daughter searched for fully five minutes within a few inches of a 
green specimen on a sweet-pea vine before discovering it. When disturbed 
the caterpillar swings down by a silken cord till it reaches the ground. Most 
of them are leaf eating and they are sometimes so numerous as to do great 
injury. Among them are the canker-worms (Fig. 135), currant span- 
worms, two or three species which feed upon the grape, and the raspberry 
geometrid. They may be poisoned by Paris green, since all insects with 
biting mouth parts can be killed by poisoning the food with arsenical 
sprays. 

1 Jackson and Daugherty's " Agriculture," p. 321. 



166 



BRANCH ARTHROPODA 



The owlet moths {Noctu'idw), of which there are more than twenty-five 
hundred species in America, fly at night and are famihar visitors around our 




Fig. 135.— The spring canker-worm: a, Egg mass, natural size; h, egg, mag- 
nified; c, larva; d, female moth; e, male moth. (Riley.) 

evening lights. To these belong the numerous cut-worm m-oths and army 
moths. Most of this large family are inconscipuous and dull colored, but 




Fig. 136. — The boll-worm or corn-ear- worm. (Riley.) 

the group of " underwings," or Catoc'alas, are exceptions to this rule. 
Strangely enough it is their posterior or under wings which are conspicu- 



LEPIDOPTERA 



167 



ously colored and banded. When at rest the inconspicuously marked 
dull-colored fore Avings completely cover the hind wings. During the day 
the moths rest close against the bark of tree trunks, where it is almost im- 
possible to distinguish them. Collectors smear syrup on the trunks of 
trees where no sweet-smelling flowers are near, and collect the insects thus 
enticed on a dark, damp night, with a dark-lantern and wide-mouthed 
bottles. 

The cotton worm {Ale'tia argilla'cea) also belongs to this family. It 
feeds upon the leaves of the cotton plants. The cotton boll-worm {Helio'- 
this armlg'era) (Fig. 136) feeds upon the pods or bolls. The destruction 
caused by these two caterpillars causes an annual loss of millions of dollars 




Fig. 137. — Corn-worm eating an ear of corn. (Quaintance, F. B. 191, 
B. Ent. U. S. D. A.) 



to the cotton growers. The boll-worm has become a great pest in the 
north also as the corn-ear-worm (Fig. 137). Just at the roasting ear 
stage it eats the juicy kernels and leaves a disgusting dark furrow, unfitting 
the corn for use. It feeds upon the fruit of the tomato also. The naked, 
greenish-brown caterpillar is marked longitudinally with darker stripes when 
grown and is about 1^ inches long. It pupates in the ground through the 
winter. The moth has dull yellowish fore wings tinged with green. 
The hind wings are paler. Since it works under cover of the husk, spray- 
ing is of no use. Fall plowing practised by all neighbors having infested 
com will materially lessen the number of worms. As the moths fly well, it 
would do comparatively little good for one to plow unless the near neigh- 
bors unite in the effort. Rotation of crops is helpful. 



168 



BRANCH ARTHROPODA 



The tussock moths (Lymaniri'idce) (Fig. 138) are of medium size, the 
antennse of the males being more broadly pectinated than those of the 
females. Ocelli are lacking. In some species the females are wingless. 
The legs are woolly or hairy. The larvae are more beautiful than the adults. 
They have several bright colored tufts of hair on the back and long pencils 




Fig. 138. — Orgyia leucostlg'ma: a, Larva; b, female pupa; c, male pupa; 
d, e, male moth; /, female moth; g, same ovipositing; h, egg-mass; i, male 
cocoons; k, female cocoons with moths carrying eggs. All slightly en- 
larged. (Howard, Farmers' Bull., U. S. Dept. of Agriculture, 1899.) 



of hair on each end of the body. The sixth and seventh segment each 
bears on the back a coral-red scent gland. It is easy to guess whether these 
caterpillars are a favorite food of birds. They infest our shade and orchard 
trees. The eggs are usually deposited upon the cocoon from which the adult 
female has just emerged, so they may be destroyed by collecting and burn- 
ing the cocoons in winter. 



169 




A B 

Fig. 139.—^, Male, and 5, female, gypsy moths. Natural size. (Forbush 

and Fernald.) 




Fig. 140. — The life cycle of the gypsy moth. (Figures after Forbush 
and Fernald.) (Bull. No. 121, New Hampshire State Experiment Sta- 
tion, December, 1905.) 



The gypsy moth {Ocne'ria di'spar) (Fig. 139), imported from Europe in 
1868, has become a great pest of forest and shade trees in Massachusetts. 



170 



BRANCH ARTHROPODA 



The state fought it in every possible way, employing hundreds of men in 
spraying, trunk-banding, and egg-collecting. From 1890 to 1900 Massa- 
chusetts spent more than a million dollars in keeping this moth in check. 
The hawk moths (Sphin'gidce), sphynx moths (Fig. 141), or humming- 
bird moths have a stout, spindle-shaped body and long, narrow, exceed- 
ingly strong wings. The sucking tube is very long, sometimes twice as 
long as the body. When not in use, it is coiled up beneath the head like a 
watch-spring. Their rich varied tints of olive, tan, black, or yellow, always 
subdued, save for an occasional dash of bright color on the under parts, 
mark them as rarely beautiful creatures. As a rule, these moths love the 




Fig. 141. — Tomato-worm or tobacco-worm: larva, pupa, 
(After Walsh and Riley, Am. Ent.) 



and adult. 



twilight, and strangely resemble the humming-birds from their habit of rap- 
idly vibrating their wings while poising themselves over a flower and suck- 
ing its nectar. 

The larva, naked and cylindric, usually has a " horn " on the back of the 
eighth abdominal segment. These caterpillars are usually green with 
several oblique light-colored or whitish Hues on each side (see Fig. 141). 
When resting these caterpillars " rear the front of the body up in the air, 
curl the head down in a most majestic manner, and remain thus rigidly 
motionless for hours. "i They are thus supposed to resemble the Egyptian 
sphynx, hence the name, sphynx moth. They feed upon the leaves of 

1 Kellogg, 331. 



LEPIDOPTERA 



171 



various trees or plants, the tomato-worm being perhaps the most familiar 
example. When full grown this is sometimes 3 inches long. The pupa, 
which lies buried in the ground, has a firm, naked, dark brown wall, and is 
distinguished by the peculiar " jug-handle " sheath, ii; which the sucking 
tube is developed. Hand picking of the larvae, fall plowing, and rotation 
of crops are the best remedies. 




Fig. 142. — Metamorphosis of monarch butterfly {Anosia plexippus): 
a, Egg; b, larva; c, pupa; d, imago or adult. (From Jordan and Kellogg, 
" Animal Life," D. Appleton and Co., Pubhshers.) 



The monarch or milkweed butterfly {Ano'sia plexip'pus) (Fig. 142) 
is one of our most abundant species. Hundreds or even thousands of 
these butterflies may sometimes be seen in a swarm, or " roosting " together 
in trees. Their wings are reddish brown, bordered with black, and the 
veins are edged with black. There are two rows of white spots on the outer 
margins. 



172 . BRANCH ARTHROPODA 

The larva when grown is a very Ught green or greenish yellow, and 
regularly marked with shiny black and yellow bands. On the second 
thoracic and the eighth abdominal segment there is a pair of slender, fleshy, 
black filaments. This caterpillar feeds upon the leaves of the milkweed. 
It attains its growth in two or three weeks, when it pupates from nine to 
fifteen days in a smooth, bright green chrysalis (Fig. 142), which is 
about an inch long and beautifully adorned with a few black and gilt spots 
and bands. In the South there are two generations, but with us but one. 

The butterfly is protected from its enemies, the birds, by an ill-tasting 
acrid fluid, of which its conspicuous color gives warning. The power of 
flight is strong and these butterflies migrate in winter. The monarch 
is found all over North and South America and in most of the Pacific 
islands, and in Australia and Western Europe. 

It is closely mimicked by the viceroy (see Fig. 92, p. 119), a smaller 
butterfly which is not distasteful, but is protected from the iDirds by its 
resemblance to the odious monarch. The viceroy may be easily dis- 
tinguished by the transverse band of black on each of the hind wings. 
Its larvae feed upon the willow, poplar, and cottonwood. The larva hiber- 
nates in a silk-lined nest made of a rolled leaf. 

The swallow-tailed butterflies (Papilion'idce) are a large and interesting 
family, having a sort of half -fluttering, half-soaring flight. They are 
easily distinguished by their large size and their black and yellow — or 
greenish-white — tiger-like markings. Twenty-one species are found in the 
United States. The wings are very thickly covered with scales. They 
are narrow and the posterior wings end in a club-shaped prolongation which 
is supposed to call the attention of the bird to the less vital part. The 
larvae when disturbed project a pair of bright colored fleshy "horns" from a 
slit in the dorsal wall of the prothorax. The horns exhale an odor which in 
some species is exceedingly disargeeable.^ 

The zebra swallow-tail {IphicU'des a'jax) differs from all other butterflies 
of the eastern United States by the black and greenish-white bands on its 
wings and by its exceedingly long " tails." This butterfly is extremely 
interesting to the scientist, in that it furnishes an example of dimorphism or 
even of polymorphism. All the broods which hatch out the same summer, 
and there may be several, are of the same form (ajax), but many individuals 
pass the winter in the chrysalis stage, some (marcellus) emerging early in 
the spring, and some (telamonides) appearing in late spring. The marcellus 
form has " tails " only about f inch long tipped with white, while the 
telamonides is a little larger, with tails nearly an inch in length and 
bordered on each side of their distal half with white; while ajax, the typ- 
ical form, is still larger and has longer " tails." 

The time of emerging seems to be the only influence controlling this 
variation, since the offspring of each form, when maturing the same season, 
produces ajax, when maturing early the following spring, produces marcel- 
lus, and late the following spring, telamonides. 

The larva of this species is light green, " thickest in the thorax," and with 
transverse markings of black dots and lines and slender yellow stripes, be- 
sides a yellow-edged, broad, black, velvety stripe on the thorax. It feeds 
upon the papaw. 

The tiger swallow-tail (Papil'io tur'nus), another common species, is also 
dimorphic. In this instance the dimorphism is sexual; at least one of the 
forms, glaucus, is represented only by the female. 

1 Comstock, r). 376. 



LEPIDOPTERA 



173 



The cabbage butterflies (Pl'eris) (Fig. 143), of which there are three 
species in the different sections of the United States, are the most de- 
structive to agricultural products of any of our butterflies. They haye 
three broods in the North and more in the South. 

The wings of Pieris rapoe are a dirty white above, tinged with yellowish 
in the female. The base and apex of the fore wings are blackish and the 
female has two black dots on the fore wings; the male has but one. There 
is a black spot on the anterior margin of the hind wing. In the male it 
is indistinct. The larva is green, with a narrow greenish-yellow band upon 
the laack and a similar narrow broken " stigmatal band." It is covered 
with fine short hairs. It feeds upon cabbage and other cruciferous plants. 
It is exceedingly hard to combat, from the facts that there are so many 




Fig. 143. — Cabbage-worm, and butterfly {Pontia ra'poe): a, Female; 
6, egg; c, worm eating on a cabbage leaf; d, suspended chrysalis; a, c, and 
d slightly enlarged. (Chittenden, Cir. 60, B. Ent., U. S. D. A.) 

broods and that the larva bores into the heart of the cabbage. The work 
of extermination must necessarily be done before the cabbage begins to 
head. Fresh pyrethrum and kerosene emulsion are helpful. It is hardly 
safe to use Paris green except with quite young plants. 

The gossamer winged butterflies (Lijcoeni'dce) include three well-marked 
groups which are commonly distinguished by their various colors as the 
" blues," " the coppers," and the " hair-streaks." They are quite small 
and delicate. The larvae are slug-like. The " blues " are often seen 
flitting about mud-puddles. Several species of the family are carnivorous. 
One of them, the " harvester " {Fenis'eca larquin'ius), common east of the 
Mississippi River, is small, with the "upper surface of wings dark brown, 
with a large irregular yellow patch on the disk of the fore wing and one of 



174 



BRANCH ARTHROPODA 



the same color next the anal angle of the hind wing." It is a friend to the 
fruit grower, for its larva feeds upon woolly plant-lice like the apple-tree 
aphis and the alder blight. 

ORDER XII. HYMENOP'TERA 

This order is represented by such famihar insects as the 
bumble-bees, yellow-jackets, honey-bees, ants, wasps, ichneu- 
mon flies, saw-flies, and gall-flies. 

The mouth parts (Fig. 144) are adapted for biting or sucking, 
the mandibles are short and fitted for biting, while the other 



Three ocelli or simple eyes 



Mandibles 

Maxillary palpi' 

Maxilla 

Labial palpi 




Compound eyes 
Antennae 
Clypeus (c). 

Labrum 

Palpifer or palpus bearer 



Paraglossse or lateral lobes 
of the tongue 

Lingula or tongue attached at 
the base of the labium 



Fig. 144. — Front view of the head of a bee. (Tenney.) 

mouth parts, as the maxillcB, labium, the maxillary and labial 
palpi, are more or less modified into a proboscis for taking up 
liquid food. 

The wings are membranous and four in number. The 
anterior pair is larger than the posterior. The student will 
observe that the body and wings of Hymenoptera are shorter 
than those of the dragon-fly order (Odonata). 

The metamorphosis is complete. The larvae are maggot-like. 

Habits. — They vary much in habits. Some are herbivorous 
(saw-flies), some form galls, others are parasitic (ichneumon 



HYMENOPTERA 



175 



flies) . The stinging Hymenoptera, on account of their efficient 
means of defense, are often mimicked (Fig. 132, p. 160) — the 
bumble-bees by the hawk-moths, the hornets by two clear- 
wing-ed moths of the genus Sesia, the bee by the drone-fly 
(Eristalis), the wasp by a common English beetle (Clytus 
erictus), and the hornet by a Nicaraguan Hemiptera. 

Saw-flies and "Horntails." — Among the boring Hymenoptera are the 
saw-flies, horntails, and gall-flies. 

The saw-flies have a wide head and thorax, with a broad joining of the 
base of the abdomen and thorax. The ovipositor consists of a pair of saws 
with which slits are made in leaves or stems where the eggs are laid. The 
larva; look much like caterpillars, but may be distinguished by having from 
twelve to sixteen pro-legs instead of ten. Most of these larvae have " a 
curious habit of curling the hind end of the body sidewise " about a branch. 
The rose-slug and currant-worm are familiar examples. 

The currant-worm is the larva of 
the saw-fly {Nem'alus ribe'sii). Tt is 
a "criminal emigrant" and has left 
a large army of descendants. The 
female deposits her glossy white eggs 
along the ribs of the first leaves of 
currant and gooseberry bushes. In 
ten days the little whitish larvae 
hatch. They are voracious feeders 
and will strip a bush of every leaf if 
allowed to mature. When mature 
they are green with a black head and 
black spots and resemble caterpillars. 
They pupate in brownish paper-like 
cocoons, either attached to the bush 
or hidden in the ground. There are 
two broods in a season, provided the 
first is not exterminated by a liberal 
spraying with Paris green or hellebore. 
If the spraying is thoroughly done 
when the worms are quite small, they are easily poisoned, since, like all 
insects with biting mouth parts, they swallow the poison with their food. 
If any of the larvae escape, the spraying must be repeated for the second 
brood, or the bushes may be killed outright in one season. If the spraying 
is done soon after the first brood hatches there is no danger of poisoning the 
fruit. 

The horntails {Siric'idoe) are so named because the posterior end of the 
abdomen bears a spine or " horn." They differ from the saw-flies in hav- 
ing an ovipositor " which is composed of live long, slender pieces," adapted 
for boring instead of for sawing. There are several species in America. 

The pigeon horntail {Tre'mex colum'ha) (Fig. 145) has a cylindric body 
about I inch in diam.cter. It is 1^ inches long, with rusty red thorax and 
black abdomen, with yellow bands and spots on the sides, a yellow " horn- 
tail," and smoky transparent wings. The female pierces holes about i inch 
deep in elm, oak, sycamore, or maple trees, bending the ovipositor at right 




Fig. 145. — Boring saw-fly or horn- 
tail {Tre'mex colum'ha). 



176 BRANCH ARTHROPODA 

angles to the body in boring, and deposits her eggs, one in each hole. 
When the larvae hatch they do much injury by burrowing into the heart- 
wood, where they feed, grow, and finally form cocoons of silk and fine bits 
of wood. The winged adult gnaws its way out through the bark. The 
ichneumon fly Thalessa is parasitic upon Tremex. 

The gall-flies {Cy nip' idee) live in closed galls during the larval state, and 
the full-grown larva either makes a hole and emerges and pupates in the 
ground, or it pupates in the gall and the adult makes a hole through which 
it emerges. The adult female pierces a hole in the tissue of the leaf with 
her sharp-pointed ovipositor which is composed of " several needle-like 
or awl-like pieces." In the incision thus made she deposits one or more 
eggs. When the larva hatches an abnormal growth of tissue begins to 
form about it, caused, perhaps, from some irritating excretions, or from 
the physical irritation caused by the pressure of the irritating body. The 
tiny, footless, white, maggot-like larva feeds, probably through the skin, 
on the sap of the growing gall. When the gall dies, which is usually about 
the time the larva is grown, it dries and hardens and forms a protecting case 
in which the larva (or larvse) pupates, and from which it emerges as a tiny 
gall-fly in the first or second spring following. 

But one of the strange things about these gall-flies is that, in some cases; 
the successive generations of the same species are not of the same form. 
The adult flies of one generation, which consists exclusively of females, lay 
their eggs upon a certain host-plant, but the resulting individuals are not 
at all like their mothers. This generation includes individuals of both 
sexes which have developed from " unfertilized eggs," or parthenogenetic- 
ally. The females of this generation lay their eggs upon a different host- 
plant, develop very differently shaped galls from those in which they 
grew up, but, like those of their grandparents, and the resulting individuals 
are like their own grandparents. Not all gall-flies show this alternation of 
generation, some species appear always in the same form, but, strange to 
say, they are usually represented only by females. Although there are 
two hundred species of gall-flies, each species infests a special part, leaf, 
branch, or root of one or more particular species of plants. The gall pro- 
duced by each species of insect is of a definite form. This is a remarkable 
manifestation of instinct. "It is impossible that intelligence or memory 
can be of any use in guiding the Cynipidoe.; no Cynips ever sees its young, 
none ever pricks buds a second season, or lives to know the results that fol- 
low the act. Natural selection alone has preserved an impulse which is 
released by seasonally recurring feelings, sights, or smells and by the simul- 
taneous ripening of the eggs within the fly. These set the whole physiologic 
apparatus in motion and secure the insertion of eggs at the right time and in 
the right place. "^ 

The Guest Gall-flies (In'quilines). — There are many gall-flies which do 
not themselves form galls, but which lay their eggs in the galls formed by 
others. The larvse feed and develop here, but do not materially disturb 
the rightful owners. 

Parasitic hymenoptera (Ichneumon' idee) are of great economic interest 
(Fig. 146). Most of them live within the bodies of their victims during the 
larval stage, the egg being laid either within or upon the body of the host. 
In the latter case the larva bores its way into the body and feeds upon the 
blood, so that the host is not killed until the larva is grown. Each species 

1 Stratton. 



HYMENOPTERA 



177 




of ichneumon flies has its special host, the majority of them being cater- 
pillars. The largest insect of this family belongs to genus Thalessa. 

Thales'sa luna'tor has a body 2h inches long and the insect measures 
nearly 10 inches from the tips of the antennae to the end of the ovipositor, 
and is parasitic upon the larva of Tremex columba. The ichneumon fly 
bores a hole with its flexible ovipositor, which is 6 inches long, into the tree 
infested by Tremex, and deposits its eggs in the burrow of the Tremex larva. 
When the ichneumon larva hatches, it creeps along the burrow until it 
reaches its victim, the horntail larva, 
to which it attaches itself and feeds 
upon its juices. Sometimes the female 
ichneumon fly gets her ovipositor fast 
in the wood and it holds her a prisoner 
until death. 

Other important, though usually 
small, parasitic Hymenoptera are the 
braconids, the ensign-flies, and the 
chalcid-flies. While the larvae of para- 
sitic Hymenoptera are degenerate in the 
same way as the footless, eyeless, an- 
tennaeless maggots of house-flies, they 
are not more so. Their parasitic habft 
has led to no such extraordinary struc- 
tiiral specialization through degenera- 
tive loss, or reduction of -parts as is the 
usual condition in other parasites. The 
adult is active and well developed. 

The Stinging Hymenoptera. — The fe- 
males and sterile workers, where there 
are such, have the ovipositor developed 
into an organ of defense, the sting. 
Females may be distinguished from the 

males by having six segments in the abdomen instead of seven, 
group includes ants, wasps, and bees. 

Ants live in all lands and in very various conditions and occupations. 
All of the 2500 or more species live in communities, and division of labor 
among kinds of individuals and, consequently, differentiation of structure, 
are highly developed. Ants are easily recognized by the form of the body, 
but they are distinguished from other insects by the character of the first 
one or two segments of the abdomen. These are expanded dorsally into a 
" lens-shaped scale or knot," which varies in form and serves as a peduncle 
to the rest of the abdomen. 

The arits' nests or formicaries are composed of irregular rooms and gal- 
leries which may be mostly underground, or have a large portion above 
ground, as a mound or ant-hill, or may be tunnelled out in the wood of de- 
cayed trees. " In the tropics," saj^s Comstock, " a greater variety of these 
structures occur than in our country. . . . One colony of one species 
has been known to have two hundred mounds covering several hundred 
square yards. Ants are also very good road makers, sometimes making 
clean beaten paths or working out covered ways under rubbish." 

There are always three classes of ants (Fig. 147) in a community, winged 
males and females, and wingless workers, sometimes also the soldiers and 
wingless, but fertile males and females. The winged males and females at 
12 



Fig. 146. — Pim-pla in the act 
of ovipositing on cocoon of tent 
caterpillar. Somewhat enlarged. 
(After Fiske.) 



The 



178 



BRANCH AKTHROPODA 



maturity issue simultaneously from the nest and from neighboring nests, 
so that the air will be filled with thousands of ants swarming about in their 
mating flight. After this the males soon die, and the females which escape 
from birds and other animals tear off their wings and go in search of a suit- 
able nesting place. Sometimes the queen starts the new colony alone, 
while in other species the workers find and adopt a queen and form a new 
colony. 

Inside the nest large numbers of very small eggs are laid in " little piles 
heaped together in various rooms and sometimes moved about by the 
workers. "1 The larvae are small, white, footless, helpless grubs, which are 
fed by the workers with regurgitated food or with chewed insects, or with 
dry seeds and vegetable matter from the granary where they have been 
stored. Most species spin cocoons in which to pupate — the white oval 
bodies seen carried away by the ants when the nest is disturbed. The adults 




Fig. 147. — The pavement ant {Tetramorium ccespitum): a, Winged 
female; b, same without wings; c, male; d, worker; e, larva of female; /, 
head of same; g, pupa of same; all enlarged. (Marlatt, Bull.U. S. Dept. 
of Agriculture.) 



are unable to escape from these cocoons unaided by the workers. The 
workers are undeveloped females or females which seldom lay eggs, and if 
they do, these eggs always develop into males. These workers not only 
feed the colony, but do all the work, building the nests and defending them 
against enemies, even by war if necessary. 

There may be from one to thirty queens, though in small colonies there is 
usually but one. As these queens grow old, the workers seek young queens 
at the swarming period and bring them into the nest. Ants, except the 
males, which are short lived, are known to live longer than most social 
insects. Lubbock says he was able to recognize worker ants at least seven 
years old, and one queen died when over thirteen years old and another lived 
more than fourteen years.- 

1 Comstock. 

2 Lubbock, " Senses, Instincts, and Intelligence of Ants," p. 233. 



Hy:MEXOPTERA 179 

Although ants are general feeders upon animal substances and fruit 
juices, thev are very fond of sweet substances like the " honey-dew " 
given off by aphids when stroked bj' the ants' antenna. In return for 
this choice food the ants shelter the aphid eggs in their nests through the 
winter and carry the young plant-lice to tender plants in the spring. When 
for any cause these plants become unsafe or unfit for the food of the aphids, 
the ants will carn.^ them to other plants. If ants are seen running up and 
down the stem of some favorite plant, one may know, unless there is a 
sweet substance exuding from bark or flower, that they are ■" pasturing their 
cows " upon the juices of tender shoots and newly forming buds. A httle 
close looking will reveal mjTiads of tuiy plant-lice on the under side or in 
the axles of the leaves. Spraying with a little dilute commercial nicotin 
will rid the plants of both ants and plant-lice. Arsenic poisons cannot 
affect aphids or other insects ha%-ing sucking mouth parts, since their food 
consists of the internal juices of plants which carmot be reached by the 
poison. 

There are many other insects u-hich live in the rtests of ants. In 1900 
Wasmann recorded 1177 insects li\-ing in the nests of ants (mjTmecoph- 
ilous insects', many of which were beetles. Most of these insects hve 
a commensal Ufe with the ants. It is not known of what advantage they 
are to their hosts. The guests, however, obtain shelter, food, moderate 
temperature, defense against enemies, and even, in the case of migrator\^ 
ants, transportation. In the case of some small beetles, however, there is 
true s>TQbio.?is with the ants, the beetles secreting a sweet substance which 
the ants eat greedily, and in return the ants ''clean, care for, and feed by 
regurgitation" the degenerate httle beetles. 

The ants furnish an example of a perfect commimistic society. There is 
no special care or favoritism for wife or child or friend, but a common love 
for the whole community. "Ever^-thing is done for the good of the whole 
and nothing for the indi\-idual. The state makes wars, provides food for 
all, cares for the children, owns all the property, the fate of each one is 
determined by the accident of birth, and each takes up its work without a 
murmur. . . . This perfect commune has developed courage, patriotism, 
loyalty, and never-failing industr\\ but also war, pillage, slavery-, and an 
utter disregard of the rights of other communities and indi\"iduals.'"i 

Most of the ants which have been described in this country can be placed 
in one of three families: (1) Formic'idae, in which is found the mt cresting 
carpenter ant (Campon'otus pennsyha' nicus) . one of the largest of our com- 
mon black ants. It builds its nest in the dead interior wood of h^-ing trees 
and wooden buildings. Here also is the mound-bmlding ant iFor'mim ex- 
sedoi'desK with its rust-red head and thorax and black abdomen and legs. 
Its ant-hills are from 5 to 10 feet in diameter. One of the most interest- 
mg of the familv is the slave-making ant (For'mica diffic'ilis). In this species 
the workers work with the slaves, but Pohjer'gus rufes'cens, a European 
species, depends upon the slaves to do all the work for the community. 
The adults are not taken captive, but in war and pillaging the larvse and 
pupge are .some of them eaten and some of them carried home, where, if not 
eaten, they develop into the adult workers, and instinctively go to work for 
their hosts, building nests, bringing food, and nursing the young. In some 
species this is carri^ on to such an extent that the hosts become unfitted for 
any work but that of warfare, and are dependent solely upon the slaves for 
shelter, food, and all the necessary work of the community. Thus their 

' Comstock, p. 634. 



180 BRANCH ARTHROPODA 

slave making has reacted upon themselves, rendering them unable to help 
themselves. It is a law in all animal life that dependence upon others 
renders one more dependent, while dependence upon self develops inde- 
pendent powers. 

The corn-louse ant (Las'ius brun'neus) is the common small brown ant of 
our pastures, woods, and meadows. It is of especial economic interest on 
account of the care it bestows on the corn-root plant-louse. The eggs of 
the plant-louse are laid in the ant's nest, where they are sheltered during the 
winter. In the spring the ants place the young aphids upon the roots of 
certain knot-weeds until the corn has germinated and then remove them to 
the corn-roots. These aphids do great damage in the Middle West. (See 
p. 144.) 

(2) Poner'idae is the smallest family in number of species, there being but 
about twenty-five known in this country, and the least specialized, that is, 
the least differentiated into castes. The queen and workers are stingers. 
Their nests are made under stones or logs. 

(3) Myrmic'idae. — This family is characterized by two segments in the 
peduncle. Usually the queen and workers have stings. The pupse are 
naked. To this family belongs the tiny " red ant " {Monomo'rium pharao'- 
nis), which is in reality a light yellow, that is the torment of housewives. 

The agricultural ants (Pogonomyrmex) live in the southern and western 
states. They, with the exception of one species, live in nests partly under 
ground, covered with conspicuous mounds in open sunny places. They cut 
away the grass immediately about the nest. It has been popularly believed 
that they sow the seed for their food, but Wheeler says that they carry out 
the debris, which consists of chaff and sprouting grain, and deposit it at the 
edge of the cleared circle. The seeds often grow and do yield a harvest for 
their next winter's stores, though not intentionally planted. 

Intelligence. — There is a great diversity of opinion among 
scientists who have experimented with ants as to the " mental- 
ity " of these insects. Bethe^ and others hold to a purely me- 
chanical or reflex theory, while Loeb, Wheeler, and others at- 
tribute to them reflexes, instincts, and animal memory, and 
Lubbock and Forel give them a considerable degree of intelli- 
gence. Comstock says they " think."^ Whether they are 
governed by one or all of these attributes, it is surely probably 
that the mechanical and chemical forces which affect the 
nervous activities of the ants may also influence those of men, 
and that if the same rigid experiments and final analyses were 
applied to the various phases of man's activities, there would 
result quite as many surprises as have accompanied the experi- 
menting upon insects, indicating that many of his activities 
are responses to mechanical stimuli, and yet no one doubts 
that man possesses intelligence. Whether the activities of ants 

1 Kellogg, 544. 2 Comstock, 637. 



HYMENOPTERA 181 

are governed by reflex action, instincts, or intelligence (in a 
limited decree, of course), or, what is more probable, by a cer- 
tain combination of these, they certainly perform many won- 
derful feats, considering the fact that they have but a single 
set of tools, the mandibles. They use these to dig and tunnel, 
to obtain food, and to carry and manipulate their food, to fight, 
to carry tenderly their eggs and young, or to cut leaves and husks 
and seeds. Though they have no voice, they are known to 
communicate by means of touch through the agency of the 
antennae. It is believed that they recognize friend or foe by 
the odor. 

The digger wasps (Spheci'7ia) are a group of closely allied families of 
Hymenoptera. They may be distinguished from true wasps by the fact 
that their wings He flat above the body, and from bees by the adaptation of 
their legs for digging and walking. They are all solitary. Each female 
makes her own nest by burrowing in the ground or in wood, or by construct- 
ing a tube of mud, or using one found already made. In this nest she places 
certain insects which she has paralyzed but not killed, by stinging, lays an 
egg, and seals up the cavity. When the larva hatches it feeds upon the food 
thus provided for it by the mother. The parasitic forms lay the eggs upon 
the paralyzed bodies of their hosts, and the guest-species lay them in the 
nests of other wasps or bees, where the larvae feed upon the food prepared by 
the host for its young. 

Famihar examples of the digger wasps are the mud daubers {Pelopoe'us) 
of our attics and eaves. It is thought that these wasps find their nests again, 
after going in search of insects with which to "provision" their nests, by the 
memory and recognition of localities, for they go from place to place, back 
and forth in many curious zigzag or circular routes, but find their way back 
to their nests readily. 

The "tarantula-killer" {Pep'sis formd'sa), of the West and Southwest, is 
a large solitary wasp which provisions its nest with the choicest of food, such 
as tarantulas, though many a hard battle is necessary to procure them. 
Sometimes the tarantula makes a meal of the wasp instead of becoming food 
for its young. 

The true wasps {Vespi'na) are characterized by the folding of their wings 
lengthwise like a fan when at rest, by the kidney-shaped eyes, and by the 
absence of bristles or spines from the legs. 

One family (Eumen'idae) of the true wasps leads a solitary life. One of 
these {Mono'bia quad'ridens) tunnels into wood and partitions ofT the 
tunnel, making a cell for each larva. 

Another species (Eu'menes f rater 'mis) is a thorough mason, making little 
jug- or vase-shaped nests of clay or mud which it attaches to the stem of a 
plant. It provisions it with caterpillars, often with canker-worms. 

The social wasps (ves'pidoe) live in communities in spring, summer, and 
autumn. The males and workers die in the autumn, and the females 
(queens) hibernate through the winter under logs or stones or in crevices. 
In the spring each queen starts a colony. She makes a small nest containing 
a few brood-cells, in each of which she lays an egg. The hatching larvae 



182 



BRANCH ARTHROPODA 



are fed by the queen with insects captured, killed, and somewhat masticated 
by herself. In a few days the larvse pupate in the cells and soon issue as 
workers. These enlarge the nest, adding new brood cells, which the queen 
fills with eggs, which, upon hatching, are fed by the workers. Thus, several 
broods of workers are reared, and the nest is continually enlarged to make 
room for the increasing family. Early in autumn a brood is hatched con- 
taining males and fem_ales, which mate probably with individuals of other 
communities, and at the approach of winter most of the colony dies, leaving 
only a few hibernating queens. 

The nest of the social wasp may be under ground, in which case it is made 
of partially decayed wood, or it may be attached to bushes or trees or under 




Fig. 148. — A hornet's nest, showing two horizontal sections of comb, one 
above the other, and the many layers of paper surrounding the nest . (Photo- 
graphed from object.) 

the eaves of buildings. This wood is formed into a pulp by being masticated 
with saliva and chewed. In the genus Polls' tes the nests consist of a single 
cone and are not inclosed in an envelop, but in the genus Ves'^a, including 
the yellow-jackets and hornets, the nest (Fig. 148) consists of several hori- 
zontal cones suspended one above the other, yet separated by a considerable 
space from each other, and the whole enveloped in a waterproof covering of 
many thicknesses of wasp-made paper, the whole nest forming a globular 
or cone-shaped ball. When the nest is to be enlarged the wasps nibble away 
the inner layers of the enveloping paste and add new layers on the outside. 
Yellow- jackets and Hornets [Vespa). — In this genus the body of the 
wasp is rather stout and short and the peduncle is very short. The color 



HYMENOPTERA 



183 



is black, spotted, and banded with yellow, from which we are all glad to 
take " warning," for the sting of a hornet is painful and the nest contains 
thousands of individuals. The queens are larger than the workers. It 
may be interesting to know that the males have no sting. They may 
be further distinguished from the other forms by having seven segments 
in the abdomen instead of six. 

The social wasps do not store up food, but continually feed the young 
throughout the larval stage, which lasts from eight to fifteen days, with 
partially masticated insects. The adults " feed upon insects or decompos- 
ing animal substances (fish especially attracts them) and upon exposed 
sweet substances, such as syrups and preserved fruits." 

Bees may be distinguished from all other Hymenoptera by their en- 
larged and flattened tarsal segments, which, except in the In'quilines, are 
provided with an arrangement for carrying pollen. It is said that the 
hairs (at least on the head and thorax) are branched or plumose, as revealed 
by the microscope, while those of all other Hymenoptera are simple. 

The nests of bees are always provided with pollen or honey, or both. 
The larvae when quite young are fed by a substance called " bee-jelly," 
regurgitated by the nurse workers; for the bee colony, like those of other 
Hymenoptera, consists of three forms: the workers, the males or drones, 
and the female (queen). ~~~- 

The short-tongued bees {Andren'idce) are all either solitary or grega- 
rious, none social. Some of the mining bees, genus Andrena, are almost as 
large as the honey-bee workers. In grassy fields they sink a perpendicular 
shaft into the ground sometimes to the depth of a foot or more, which 
branches off sidewise to the cells. Though each nest is solitary, the females 
often build close together. 

The smallest of our bees (Hallc'tus) burrows in sand-banks or clifts. 
Several females unite to " make a burrow into the bank, after which each 
female makes passages extending sidewise from this main burrow or 
pubhc corridor to her own cells. While Andre'na builds villages composed 
of individual homes, Halictus makes cities composed of apartment houses. "i 
The long-tongued bees (A'pidce) have the lower lip highly specialized 
for obtaining nectar from flowers. The basal segment of the labial palpus 
is also elongated. Some of this family are solitary; others, guest-bees; 
a few, social. 

Among the solitary long-tongued bees is Megachi'le acu'ta, a carpenter 
and leaf-cutter, which, if it does not find a convenient crevice or cavity 
ready made, tunnels out a tubular cavity in wood and builds a thimble- 
shaped nest at the bottom out of oblong pieces of leaves which it cuts out 
for itself, and fills it with a paste of pollen and nectar. The egg is then 
placed upon this food and the opening tightly plugged up with circular 
pieces of leaves. 

The little blue carpenter bee {Ccrat'ina du'pla) builds its nest in dead twigs 
of sumach or in the hollows of other plants. The female fills the bottom of 
the nest with pollen, lays an egg upon it, and makes a partition above the 
egg out of pith chips made in forming the tunnel. She continues making 
these cells until the tunnel is nearly full, then she rests in the space above the 
last cell and waits until the young are grown. When the first one is 
ready to emerge, it tears down the partition above it and waits till each one 
has performed the same process, when they are led by the mother into the 
open air. Comstock says it is the only instance he knows of a solitary 

1 Comstock, p. 666. 



184 BRANCH ARTHROPODA 

bee watching her nest. The old nest is cleaned out by the whole family 
and used again by one of them. 

The guest-bees {In'quilines) infest the nests of both solitary and social 
bees, sometimes being unwelcome guests. They have, of course, no 
worker forms, only males and females, since work is not necessary when 
they can live off the bounty of others. Those infesting the nests of 
solitary bees steal into the nest before it is completed and lay their eggs, 
which hatch before those of the host, and devour the food intended for the 
young of the rightful owner. Strangely enough, the Inquilines {Psith'yrus) 
seem to be welcome, for if they were not the bumble-bees surely would 
drive them out, for they certainly could. The female lays her eggs in a 
bumble-bee's nest, and when the larvae hatch they are cared for by the bum- 
ble-bees as if they belonged to them. Sometimes the guests very closely 
resemble their hosts in size and color, but in other cases they are marked 
very differently. The males resemble the bumble-bees so closely in ap- 
pearance and structure that it is difficult to determine whether they belong 
to Psithyrus or Bombus, but the females are easily distinguished, for the 
pollen-basket of the hind legs has been lost through disuse. There are 
no workers among the Psithyrus, and if for any reason the supply of the 
host should fail them, the guests would starve, for they are so degenerate as 
to actually be unable to work. Kellogg says these guest-bees " are like 
bumble-bees in so many structural details unnecessary for deception (mim- 
icry) that they must be looked on as a degenerate offshoot from the Bom'- 
bidce," that is, as degenerate bumble-bees. 

The social bees, which are native, belong to the genus Bombus. The 
bumble-bees, like the ants, live in communities having three kinds of in- 
dividuals: males, females, and workers. In early spring each queen which 
has survived the winter by hibernating seeks some unoccupied mole's nest 
or mouse's nest or digs a cavity in the ground for her nest. In this she 
deposits a ball-shaped mixture of pollen and honey and lays a few eggs, 
not over twenty, upon it. Then she brings another supply of food and de- 
posits more eggs. When the first larvae hatch they feed upon the food 
provided, and when grown each spins a silken cocoon and pupates. These 
all form worker bees, which enlarge the nest and provide more food. The 
queen lays more eggs and the workers now enclose the larvae in waxen 
cells. A few cells also are filled with pollen or with honey. The nest 
may become as large as one's head and is covered loosely with bits of vege- 
tation. It usually has two or more openings. " Later in the summer males 
and females appear, and it can be said to the credit of the bumble-bee queens 
that they are not jealous, but allow the young queens to live with them in 
the nest." In early winter all bumble-bees perish except the young queens, 
which hibernate in some crack or crevice. There are more than fifty species 
of bumble-bees (Bombus) in the United States. They differ in size and in 
the arrangement of the black and yellow color-patterns. 

The honey bee is a native of Europe, but has been domesticated the 
world over. " It has been known and cared for by men for centuries. 
There are two genera: (1) Melipona, which has the sting blunted and ap- 
parently never used as a weapon, lives in the tropics and consists of numer- 
ous species which have been little studied. (2) Apis has but few species, 
one of which is our common hive bee. 

The community consists normally of one queen, from less than a hundred 
to several hundred males, and from about 10,000 workers in winter to 50,000 
in summer. The queen (Fig. 149, K) may be known by her long slender ab- 



HYMENOPTERA 



185 



domen and by the absence of wax plates, planta, and pollen baskets. The 
queen is hatched from a fertilized egg in a large cylindric, vertical cell 
(Fig. 149, 6-10), and fed almost wholly upon bee-jelly regurgitated by the 
nurse workers. Here, at least, is one strong example of the influence of 
environment during development, for it has been proved that there is no 
difference between the egg from which the queen is developed and the one 
which develops into the worker. 

Theworkers (Fig. 149, A), which are the bees we commonly see, are srqaller 
than the queens and males. They are hatched in hexagonal, horizontal 




Fig. 149. — Hive bees and comb (after Schmeil). A, Worker; K, queen; 
D, drone; 1, worker with cells filled with honey and covered; 2, cells con- 
taining eggs, larvae, and pupse; 3, cells containing pollen; 4, below 4 are 
regular cells; 5, drone cells; 6-10, queen cells. 

cells, and fed, like the males, with honey and bee-bread. " Workers have 
wax plates under the abdominal segments and pollen baskets on the outer 
surface of the hind tibiae." 

The males, or drones (Fig. 149, D), have a hairy thorax and a heavy, 
broad, blunt body, and, like the queen, lack the special structures of the' 
workers. They are hatched in the larger, hexagonal, horizontal cells from 
" unfertilized " eggs. After the swarming season is over, the males are 
driven out of the hive or stung to death by the workers. 

When a community becomes too large, the workers prepare a " queen- 
cell " and develop a queen by process of special feeding and care, or, it 



186 



BRANCH ARTHROPODA 



may be, several queens are so developed. When these young queens emerge, 
the old queens at once enter into battle with them. All new queens are 
killed but one, which the workers guard. The old queen leaves the hive 
accompanied by a swarm of workers and founds a new colony. The work- 
ers at once begin to secrete wax by gorging themselves with honey and then 
together " hang quietly in a curtain-like mass, the upper bees clinging to 
the roof of the hive and the lower ones to the bees above them. After 
about twenty-four hours there appear little flakes of wax that are forced 
out from openings between the ventral abdominal segments, called wax- 
pockets. These wax scales continue to increase in area and soon pro- 
ject beyond the margin, and either fall off or are plucked off by other workers 
or by the wax-producing worker itself. "^ Other workers construct it into 
comb, the trowel-like mandibles pressing it into hexagonal cells. Each 
comb consists of a double layer of cells separated by a common partition. 
New wax is used in forming cells for storing honey, but old wax or wax 
mixed with pollen may be used for brood-cells. The workers also carry 
" 'propolis," a sticky, gummy substance with which they at once stop the 
chinks of their hive. They carry water also to the thirsty larvae. By 
steadily and rapidly vibrating their wings a set of workers stationed at the 
exit or scattered about the floor form currents of air, thus ventilating the 
hive. Another set acts as scavengers and carry off all dead and decaying 
debris from the floor and walls. Still another set guards the entrance from 
intruders, such as neighboring bees, yellow-jackets, and bee-moths. For 
guarding against the minute bee-lice and bacterial diseases the help of man, 
" the bee-keeper," is needed. Kellogg gives an observation hive and how 
to make it, which would be well worth trying. For after you have studied 
carefully these, shall I say, intelligent little creatures you will find it, indeed, 
difficult to decide which of their actions are reflex, instinctive, or intelHgent, 
or which are all of these combined. 

Classification. — ■ 

Class I. Crusta'cea. 

Sub-class En'tomos'traca. 

Order I. Phyllop'oda. 

Order II. Ostrac'oda. 

Order III. Copep'oda. 

Order IV. Cirripe'dia. 
Sub-class Mal'acos'traca. 

Order I. Phyllocar'dia. 

Order II. Decap'oda. 

Order III. Arthros'traca. 

Class II. Arach'nida. 

Order I. Scorpion'ida. 

Order II. Phalangi'da. 

Order III. Arane'ida. 
Order IV. Xiphosu'ra. 



Brine shrimp. Daphnia. 

Cypris. 

Cyclops. 

Barnacles. 

Nebalia. 

Crayfish, lobsters, crabs. 

Gammarus. Pill-bug. 

Scorpions. 
' ' Daddy-long-legs . ' ' 
Spiders. 

Limulus or Horseshoe 
Crab. 



1 Kellogg, p. 526. 



HYMENOPTERA 



187 



Class III. Myriap'oda. 

Order I. Chilop'oda. 

Order II. Diplop'oda. 

Class IV. Insec'ta. 

Order I. Ap'tera, or Thys- 

anu'ra. 

Order II. Ephemer'ida. 

Order III. Plectop'tera. 

Order IV. Odona'ta. 

Order V. Isop'tera. 

Order VI. Corroden'tia. 

Order VII. Malloph'aga. 

Order VIII. Euplexop'tera. 

Order IX. Orthop'tera. 

Order X. Physop'oda. 

Order XI. Hemip'tera. 

Order XII. Neurop'tera. 

Order XIII. Mecop'tera. 

Order XIV. Trichop'tera. 

Order XV. Lepidop'tera. 

Order XVI. Coleop'tera. 

Order XVII. Dip'tera. 

Order XVIII. Siphonap'tera. 

Order XIX. Hymenop'tera. 



Centipedes. 
Millipeds. 

"Fish-moth" and "spring 

tails." 
May-flies. 
Stone-flies. 
Dragon-flies. 
Termites. 
"Book-lice." 
"Bird-hce." 
Earwigs. 

Grasshopper, katy-did. 
Thrips. 
Chinch-bug, plant lice, 

and cicada. 
Aphis-lion, ant-lion. 
Scorpion-flies. 
Caddice flies. 
Butterflies, moths. 
Beetles. 
Flies. 
Fleas. 
Ants, wasps, bees. 



BRANCH CHORDATA 

Branch Chordata comprises many of our best-known and 
valued animals. 




Ill ni , HI . ^'^ 

Fig. 150. — A series of embryos at three comparable and progressive stages 
of development (marked I, II, III), representing each of the classes of 
vertebrated animals below the Mammalia. (After Hackel.) 

188 



BRANCH CHORDATA 189 

Characteristics. — They all have (1) Gill-slits in their embry- 




nr HI IE HI 

Fig. 151. — A series of embryos at three comparable and progressive 
stages of development (marked I, II, III) , representing four different di- 
visions of the class Mammalia. (After Hackel.) 

onic life or they may be permanent; (2) a notochord; (3) a nerve 
chord or nervous system dorsal to the notochord. The noto- 



190 



BRANCH CHORDATA 



chord is a smooth, elastic rod typically developed from the endo- 
derm, extending along the median line between the alimentary 
tube and the central nervous system. It is encased in a tough 
sheath or membrane and "forms an elastic supporting structure." 




Fig. 152. — Ideal primitive vertebrate, seen from the left side: na, Nose; 
au, eye; md, mouth; g, ear; ks, gill openings; x, notochord; mr, spinal tube; 
kg, gill-vessels; k, gill-intestine; hz, heart; ms, muscles; ma, stomach; 
V, intestinal vein; c, body cavity; a, aorta; i, liver; d, small intestine; e, 
ovary; h, testes; ri, kidney-canal; af, anus; Ih, true or leather skin; oh, 
outer skin (epidermis); /, skin-fold, acting as a fin. (After Hackel.) 

In the higher forms the notochord is replaced by a segmented 
cartilaginous or bony vertebral column. 

These three characteristics may not be easily recognized by 
the beginner as he looks at the worm-like Bal'anoglos'sus, the 




Fig. 153. — The same in transverse section through the ovaries; lettering as 
in the preceding figure. (After Hackel.) 



sac-like sea-squirt, or the small fish-like or worm-like Am'phiox'us 
or Lance'let, but, passing by these low forms to the fishes, frogs, 
reptiles, birds, and mammals, one readily finds that the body has 
two cavities instead of one, as in the invertebrates. 



ADELOCHORDA 



191 



Neural Cavity. — The upper or neural cavity contains the brain 
and the spinal cord. 

Hemal Cavity. — Below the vertebral column with its neural 
cavity is the large cavity of the body, the hemal cavity, which 
contains the heart, lungs, digestive organs, and other viscera. 

Skeleton. — Most of these higher forms have an internal bony 
skeleton or a cartilaginous one, as in some fishes. The vertebral 
column, or backbone, is composed of a varying number of bones, 
each called a vertebra, hence the branch is named Vertebrata, 
or, if named from the notochord, Chordata. 

Divisions of the branch are usually 
made to distinguish the primitive groups 
(Fig. 152) or Protovertebrates, from the 
true Vertebrates. 

The Protovertebrates congist of three 
separate groups or sub-phyla, not closely 
related to each other, but each, in a 
primitive way, is entitled to relationship 
with the Chordata or Vertebrata. 

SUB-PHYLUM AND CLASS I. 
ADELOCHORDA 

The Balanoglossus is the principal 
genus of this group, though two deep- 
sea forms {Rhabdo'pleu'ra and Ceph'alo- 
dis'cus) have a notochord, and the latter 
has a pair of gill-slits, but in other ways 
they are like the polyzoans. The Bal- 
anoglossus (Fig. 154) is a small marine 
chordate. Its surface is ciliated. It is 
from 1 to 4 or 5 inches in length, and, by 
means of its proboscis, burrows in the 

mud along the seashore. A study of the animal or of a good 
figure will show that it has (1) a dorsal nerve cord, (2) a 
notochord, and (3) gill-slits. 

Body Regions. — The Balanoglossus is divided into three 
body regions: the proboscis, a club-shaped hollow anterior por- 
tion opening exteriorly by a single pore; back of the proboscis 




Fig. 154. — Balano- 
glossus: p, Proboscis; 
c, "collar"; gs, gill- 
slits; enlarged. (From 
Dodge's " General Zo- 
ology," American Book 
Co., Publishers.) 



192 BRANCH CHORD ATA 

is the collar, opening by two spores into the first gill-slit; the re- 
mainder constitutes the flattened but nearly cylindric trunk. 
There is no segmentation of the body. By alternately contract- 
ing and dilating the proboscis and the collar the Balanoglossus 
can burrow in the mud. 

Gill-slits. — On the dorsal surface of the anterior portion (the 
branchial region) of the trunk is a double row of gill-slits which 
increase in number throughout life. 

Digestive System. — The mouth is situated ventrally at the base 
of the proboscis just within the collar, and from it the alimentary 
canal extends to the posterior extremity of the body. "Into the 
dorsal half of the anterior portion of the alimentary canal open 
the internal gill openings." The hepatic cceca bulge out in ex- 
ternal prominences in the middle part of the canal. The 
anal opening is at the posterior end of the body. 

The notochord, "a blind tube surrounded by a tough mem- 
brane, extends from the pharynx into the proboscis." There are 
dorsal and ventral nerve strands connected by nerves in the 
collar. 

A dorsal hlood-vessel lies above the notochord. 

The larvae of some species so much resembles certain echino- 
derms that the Balanoglossus was formerly placed with that 
branch. 

SUB-PHYLUM AND CLASS 11. UROCHOR'DA OR 
TUNICATA 

This degenerate group is represented by minute animals a few 
centimeters long and by some measuring several feet in length. 
They are found singly or in string-like colonies which have been 
developed from a solitary individual by budding, the two forms 
thus giving rise to alternation of generations. Multiplication 
is both sexual and asexual. They are hermaphroditic, but cross- 
fertilization occurs. They are marine and most of them are 
pelagic. 

The most common forms, the " sea-squirts" or ascidians (Fig. 
155), are surrounded by a tough elastic bag, one end of which is 
attached to stones. At the other end is a large round oral 
aperture, for the inlet of water carrying food and air, and near it. 



UROCHORDA OR TUNICATA 



193 



on one side, is the atrial aperture, for the exit of the current. 
Sea-squirts are destitute of head and Hmbs. The ventral heart 
enclosed in a pericardium is situated between the gill region and 
the stomach. This heart has the peculiarity of changing the 
direction of its contractions. When the blood has been driven 
to the gills for a while it rests a little, and then forces the blood 
in the opposite direction. 




Fig. 155.— Diagram of the growth of a sea-squirt or ascidian: A, a, young 
free-swimming stage; a^, intermediate stage just before becoming fixed. 
B, b, Full-grown sea-squirt, rooted to the sea bottom and incapable of 
movement: m, mouth; e, hollow brain with eye; g, gill-slits; h, heart; r, rod 
of gristle in free-swimming form; nv, nerve cord in same; t, tail in process 
of absorption in intermediate form. (After Haddon.) (From Baskett, 
" The Story of the Fishes," D. Appleton and Co., Publishers.) 



The "sea-squirts" were formerly called "Tunicates," until a 
study of their larval stage showed them to have vertebrate char- 
acteristics. The larva has a slender finned tail containing a 
notochord and a nerve cord. They furnish an example of retro- 
grade development. They are free for a few hours, then be- 
come fixed and lose the notochord and nearly all traces of their 
vertebrate characteristics which promised a higher develop- 
ment. 

13 



194 



BRANCH CHORDATA 



wt! 



SUB-PHYLUM AND CLASS III. ACRA'NIA OR AMPHIOXUS 

This is a small fish-like chordate 2 or 
3 inches in length. 

Its shape is one found for the first time, 
that of narrow ventral and dorsal sur- 
faces and deep lateral surfaces. It is 
pointed at both ends. It falls on its side 
when not in motion. 

It is marine and lies buried in the 
clean sand along warm seacoasts, with 
its cihated lips protruding. The currents 
produced by the cilia bring fresh water 
with its oxygen to the gills. Small organ- 
isms are also thus furnished for food. 

The Am'phiox'us (Fig. 156) has no 
limbs, no skull, no well-differentiated 
brain, and no heart, but it has a noto- 
chord (a smooth cylindric rod lying above 
the alimentary tube), a nerve cord dorsal 
to the notochord, numerous gill-slits, 
and an alimentary tube. The sexes are 
separate. 

The alimentary tube is a straight tube 
consisting of mouth, pharynx, and in- 
testine. On the right side of the pharynx 
is a blind pouch, the so-called liver. 

The circulatory system consists of a dor- 
sal arterial trunk and a ventral venous 
trunk connected by lateral arches. The 
blood is colorless. 

Fig. 156. — Amphiox'us lanceola'tus : a, Anus; 
au, eye; h, ventral muscles; c, body cavity; ch, 
notochord; d, intestine; do and du, dorsal and 
ventral walls of intestine; /, fin-seam; h, skin; 
k, gills; ka, gill-artery; lb, liver; Iv, liver-vein; 
m}, brain vesicle; m^, spinal marrow; 7ng, 
stomach; o, mouth; p, ventral pore; r, dorsal 
muscle; s, tail fin; t, t, aorta; v, intestinal vein; x, boundary between gill 
intestine and stomach intestine; y, hypobranchial groove. (After Hackel.) 



CYCLOSTOMATA 195 

Locomotion. — The Amphioxus has a median dorsal fin which 
extends over the tail both dorsally and ventrally. The tail, 
that portion of the body posterior to the alimentary tube and 
filled with muscle, is the chief organ of locomotion. It is noc- 
turnal, swimming about at night, but quickly returns to its 
burrow if disturbed. It can burrow in the sand with either head 
or tail. 

Nervous System. — A simple dorsal nerve lies above the noto- 
chord. It does not reach entirely to the front of the body. Its 
anterior tip is called the cerebral vesicle, in which there is an 
eye-spot. There is also possibly an olfactory organ consisting 
of a simple pit reaching from the skin down into the anterior 
tip of the nerve cord. 



SUB-PHYLUM IV. CRANIA'TA OR VERTEBRA'TA 

These are chor dates having a brain or skull. The group 
includes fishes, amphibians, reptiles, birds, and mammals. 
The body is usually elongated and more or less cylindric. 
The mouth is situated anteriorly. Ventrally and near it, ex- 
cept in Cyclostom'ata, are the paired nostrils. Situated in 
the head there are also a pair of eyes and a pair of ears, 
though the ears are not always external. Gill-slits are 
never more than seven in number, and partially or alto- 
gether disappear in the adult air-breathing forms. There 
are one or two pairs of jointed limbs, but in some cases they 
are rudimentary or wanting. 



CLASS I. CY'CLOSTOM'ATA 

The animals of this class inhabit both fresh and salt water. 
They have no lower jaw. The mouth is suctorial, the skull 
cartilaginous, the notochord persistent, and the teeth horny. 
The neural arches are rudimentary. There are no limbs or 
scales and no paired fins; but unpaired dorsal and caudal 
ones are present. The class includes the lampreys (Fig. 
157) or "lamprey-eels" and the hag-fishes. The skin is 



196 BEANCH CHORDATA ' 

slimy and very smooth. The gills of the lampreys open into a 
respiratory tube lying below the gullet. 




Fig. 157. — Lamprey {Petromy'zon mari'nus). (After Goode.) 

They are parasitic on fishes and also devour crustaceans. The 
slimy eels bore into fishes and eat the flesh. 

CLASS n. PIS'CES 

To this class belong the true fishes, common examples of 
which are the sunfish, perch, salmon, catfish, carp, and trout. 
They are aquatic, gill-bearing, poikilothermal, usually scaly, 
bilaterally symmetric finned chordates. 

Shape. — The typical fish is wedge shaped (Eig. 158) at both 
ends, so that it can pass rapidly through the water. The head 
is large and pointed, with the viscera situated near it, while the 
trunk is long and tapering, for the attachment of muscles to flex 
the tail in locomotion. Usually the body is more or less flat- 
tened from side to side, though it may be quite cylindric, as in 
the eel, or flattened dorsoventrally, as in the adult flounder, or 
the body may be long and slender, as in the pipe-fish and ribbon- 
fish. The shape conforms largely to the habits and habitat. 
The fishes having the under side flattened usually swim near or 
rest upon the bottom at some time, as our catfish, but the broad 
forms, flattened above and below, like the skates and flounders, 
live upon the bottom and are not built for speed. The ''flat 
fishes" in early life have the position common to most fishes, but 
in adult life the dorsoventral plane becomes horizontal instead 
of vertical, the eye lies upon the upper side, and the color of the 
upper side becomes dark like the dorsal side of most fishes, and 
the under side light like the ventral side. 



PISCES 



197 



Size and Number. — Fishes vary in length from an inch or less 
to 30 or 40 feet. Kellogg says there are about "15,000 species 
of fishes known, of which 3000 species live in North America." 
Is it any wonder they vary in size, color, and habits? They are 
the best adapted of all vertebrates for an aquatic life. 

Covering. — The epidermis consists of many layers of proto- 
plasmic cells with a very thin cuticle. The secretion of mucus 
by the great numbers of "slime-cells" of the epidermis gives to 
fishes their slippery skin. The epidermis contains also pigment 
cells. The dermis consists of numerous layers of connective 




Fig. 158. — Figure of a whitefish, showing the location of parts usually 
referred to in descriptions: 1, Dorsal fin; 2, adipose fin; 3, caudal fin; 4, 
anal fin; 5, pectoral fin; 6, ventral fin; 7, lower jaw, or mandible; 8, upper 
jaw, or maxillary; 8a, supplemental maxillary; 9, opercle; 10, branchioste- 
gals; 11, caudal peduncle; 12, lateral line; 13, series of crosswise scales usually 
counted; 14, snout; 15, eye; 16, head; 17, depth; 18, base of caudal; 19, dis- 
tance from snout to nape or occiput. (Report U. S. F. C, 1894.) 

tissue and furnishes the dermal or exoskeleton or scales which are 
usually embedded in pockets of the dermis. 

In many fishes the scales overlap each other. In the brown 
trout, for example, the greater portion of each scale lies under 
the one anterior to it, and the remainder, a small triangular por- 
tion, is covered by the epidermis only. The scales sometimes 
receive a layer of enamel or vitrodentin from the epidermis. 
(1) The placoid scales are rhombic, plate-like bodies often bearing 
a spine covered with vitrodentin. These scales are placed close 
together, but do not overlap. (2) The ganoid scales also are 



198 BRANCH CHORDATA 

generally "rhomboid and arranged like parquetry." They are 
covered with a thick coating of vitrodentin which gives an 
iridescent effect, and are often closely articulated into a coat of 
armor. (3) The cycloid scales are closely related. They are 
placed loosely in the pockets and arranged in rows. In over- 
lapping, one scale covers parts of two scales posterior to it. The 
middle part of the scale is surrounded by concentric lines from 
which proceed radiating lines. (4) The ctenoid scales (see Fig. 
174) have the posterior edges truncate and the free margin 
toothed. The scales are often striated or polished, and this 
gives rise to various colors, especially the iridescent gleam on 
the sides of the fish. 

Color. — The color in general harmonizes with its environment. 
Most of the fresh-water fishes are dark colored (olive or greenish) 
above and whitish below, so that to the enemies from above, 
as fish-eating birds, the form appears indistinct in the water, and 
to the enemies below they look white like the light. Many are 
variously dotted or striped with lighter or darker colors, thus 
simulating the lights and shadows among the weeds and grasses. 
The scales reflect all the hues and tints of the rainbow, causing 
the fishes to rival the birds in beauty. The males of some species 
put on brighter colors at the spawning season. Some species 
have the power of changing color at once to meet the surround- 
ings, as the pipe-fishes, some sticklebacks, the plaice, and the little 
OUgocottus snyderi, of Monterey Bay, California. Many others 
change the colors more gradually. Recent experiments upon 
fishes in aquaria have shown that if the light be thrown from 
below and cut off from above, the upper part grows light colored 
and the lower part dark colored. This would seem to show that 
the colors are due to the action of light, but while many fishes 
in caves are colorless, it is said that those in the black depths 
of the ocean may be either pearly white or black; so the question 
is yet unsolved. Many deep-sea forms are phosphorescent. 

Some fishes have special protective resemblance, as the leaf- 
finned sea-horse, the pipe-fish, and some angler-fishes, the pos- 
terior fins of which are bedecked with fringes "that exactly 
mimic seaweed." The mouse-fish, or Sargassum, is colored to 
harmonize with the gulf weed, Sargassum, among which plants 
it lives. 



PISCES 199 

" The color of fishes is of threefold origin. The silvery luster is due to 
crystals of guanin which occur in the skin. The other colors are due 
partly to numerous strongly pigmented fat-cells and partly to the chro- 
matophores in the derma, which under the control of the nervous system 
can alter their forms and extent and thus produce color changes in the 
fish, thus adapting it to its surroundings. It is of interest to note that 
destruction of the eyes results in loss of power to change color. "^ 



Locomotion and Appendages. — The appendages of fishes, ex- 
cept in rare instances, are the unpaired dorsal, anal, and caudal 
fins, and the paired pectoral and ventral fins. "Fishes are 
the only vertebrates having median fins supported by fin-rays." 
The fin-rays supporting all the fins are of dermal origin. The 
locomotion is mainly produced by the flexing of the body and 
tail, so as to propel the usually spindle-shaped animal through 
the water. The fins aid in^directing the movements of the fish, 
as does also the air-bladder, which regulates the specific gravity 
of the fish. 

The skeleton is cartilaginous or bony. The notochord of the 
protovertebrate becomes surrounded by a mesodermic sheath 
which produces the centra of the vertebrae, consisting of cartilage 
or bone. From the centra are outgrowths dorsally which give 
rise to the neural tube, "an inverted tunnel of cartilage" en- 
closing the cerebrospinal cavity, and ventral (hemal) outgrowths 
protecting the viscera. The vertebrae are usually amphicelous, 
and the notochord persists in the cavities between the centra. 
The neural arches extend throughout the spinal column, while 
the hemal are complete only in the tail. In the trunk the 
hemal spines are absent and the hemal processes are divided 
into basal processes and ribs which surround the viscera. There 
is no sternum. 

The skull (Fig. 159) encloses the brain which does not fill the 
cavity. The lower jaw is movable and usually bears teeth. 
Some fishes have many teeth; others, few or none. They have 
no other prehensile organs. 

The pectoral and ventral fins are homologous with the paired 
limbs of the higher vertebrates, but lack many of the bones of the 
higher forms, as a comparison of the bones of man's arm with 
those of the pectoral fins will show. 

1 Hertwig's " Manual of Zoology," Kingsley, p. 559. 



200 BRANCH CHORDATA 

Digestive System. — The food is principally animal. Food 
securing is, of course, by the mouth. The mouths of fishes vary 
in size, shape, and position, according to the food and feeding 
habits. The digestive tract is large, near the region of the phar- 
ynx, but narrows into a tube in which there is little distinction 




Fig. 159. — Right lateral view of skull of M. dolomieu, with other bones; 
natural size: Pmx, premaxillary ; PI., palatine; na., nasal; Eih., ethmoid; 
Prf., prefrontal; As., alisphenoid; Fr., frontal; Ptf., postfrontal; Sq., 
squamosal; Pa., parietal; Pt.o., pterotic; S.O., supra-occipital; s.l., supra- 
linear; Ep.o., epiotic; k, interneural spines; La., lacrymal; Pr.s., para- 
sphenoid; S.or., suborbital; Pr.o., prootic; Bs., basisphendid ; G.Hy., 
glossohyal; D,. dentary; Art., articular; Mx., maxillary; a, admaxillary; 
Enpt., entopterygoid ; Ecpt., ectopterygoid; M.Pt., metapterygoid; 
Pst.T., posttemporal ; Pr.s., proscapula; Pf., pectoral fin; Hyo.C, hypo- 
coracoid; Op., operculum; S.Op., suboperculum ; Aug., angular; Sym., 
symplectic; n.s., neural spine; Fsto. T., posterotemporal; 7", teleotemporal; 
T', lower teleotemporal ; Bs.R., branchiostegal rays; P. Op, preopercu- 
lum; I.Op., interoperculum; H.M., hyomandibular; Qu., quadrate; r., rib; 
AsL, actinosts; Hyp.C, hypercoracoid. (Shufeldt.) 



between the parts. Many fishes have pyloric ceca at the junc- 
tion of the stomach and intestine. Others have a spiral valve, 
a fold of mucous membrane increasing the digestive surface. 
There is a large liver and a spleen and usually a pancreas and 
gall-bladder. 



PISCES 



201 



Excretion. — The nephridea unite in a pair of large kidneys. 
The ureter may or may not empty into a urinary bladder. 

Circulation (Fig. 160). — ^The heart is surrounded by a peri- 
cardium. It consists of sinus venosus, auricle, ventricle, and 
conus arteriosus. The blood, which is red, goes from the gills 
over the body. The veins collect it and return it to the sinus 



Branchial arterys^ 

Arterial bulb «.,_ 
Ventricle of the heart -^.. 

Auricle of the heart- 

Venous sinus- 
Vena portse, liver, etc."! 



Intestine'—' 



Vena cava" 




Branchial vessels 



—Dorsal artery 



Kidneys 



Dorsal artery or aorta 



Fig. 160. — The circulatory apparatus of a fish. (Tenney.) 



venosus, from which it passes through the parts of the heart in the 
order named, and the circulation begins anew. 

Respiration is by gills except in the lung fishes, which take the 
mechanically dissolved air from the water and give off waste 
matter. The gills arise as paired pouches of the pharynx and 
open on the exterior by gill-slits. They are attached to the 
branchial arches and are persistent through life. 



202 



BRANCH CHORDATA 



The brain is of the vertebral type, but small, and occupies but 
a small portion of the cranium. The cerebrum is comparatively 
small. The cerebellum is sometimes large. The optic and ol- 
factory lobes are conspicuous (Fig. 161). The medulla is also 
present, all the parts being distinct and visible from above. 
The brain sends off at least ten pairs of 
nerves. 

The Senses. — Of all the sense organs, 
the most noticeable are those along the 
lateral line. The lateral line on either 
side of the fish from tail to head is 
"marked by a groove in the scales which 
opens to the exterior by numerous canals 
through the scales." (Examine several 
scales along the lateral line.) The func- 
tion of the lateral line is possibly to as- 
certain the water pressure at different 
depths. 

The skin and especially the lips are 
the seat of the sense of touch. 

The eye has several peculiarities. The 
lens is very convex, owing to the slight re- 
fraction from the light in passing from the 
water into the cornea. The eye is short sighted, since light is 
so absorbed by water as to render objects a short distance away 
invisible. Lids are wanting or very poorly developed. Only 




Fig. 161.— Brain of 
a cod: og, Olfactory 
ganglia; ch, cerebral 
hemispheres; ol, optic 
lobes; c, cerebellum; 
mo, medulla oblongata. 
(Tenney.) 




Fig. 162. — Lucifu'ga. A blind fish containing unborn young with well- 
developed eyes. (Eigenmann, Bulletin 526, U. S. F. C, 1902.) 



a few fishes have a nictitating membrane. There are no tears. 
Through disuse for generations the cave fishes have lost their 
sight (Fig. 162). 



PISCES 



203 



The ear^ has a relative size found in no other vertebrate. 
There are no external ears. Many teleosts have two otoliths. 
Experiments show that the ear is principally for a balancing 
organ. 




Fig. 



163.— Stickleback and nest. (From Baskett, "The Story of the 
Fishes," D. Appleton and Co., Publishers.) 



1 " The maigre is said to produce a flute-like note audible in twenty 
fathoms. Many fishes utter sounds, but perhaps the grunt {Hoemulon) 
on the outer Florida reef is most remarkable for the variation of the sound. 
. . . The dog-fish utters a croak or bark. The gizard-shad (Hippo- 
campus), eels, catfish, porcupine-fish, sunfish, carp, gurnards, etc., utter 
sounds either accidental or intentional. The sound, a single note, fre- 
quently uttered by the eel is, according to Abbott, more distinctly mu- 
sical than those made by other fishes." (Holder.) 



204 



BRANCH CHORDATA 



The function of the nostrils is smelling and not breathing. 
For none of them, except those in the hag-fish and lung fish, open 
into the mouth. The odors must come through the water. All 
fishes proper have two nostrils. Experimental proof of smell is 
lacking, but the well-developed olfactory lobes and nerves argue 
that the sense cannot be entirely wanting. 

Emotions. — If you have ever tried the sport of fishing with 
hook and line, you know that fishes have emotions of fear and 
curiosity. Romanes says they have also those of play, anger, 
pugnacity, and jealousy. In some species parental affection is 
proved by the building of nests (Fig. 163) and the care of the 
young; sexual feelings, by courtship; social or gregarious in- 
stincts, by their "schools."^ 




Fig. 164.— Sawfish. 



s^^^:::? 



Upper, profile view. Lower, view of under part. 
{Pristis pectinatus.) 



Means of Defense. — Fishes most often protect themselves 
from their enemies by their close resemblance to the surround- 
ings, or by their swift movements, darting away at the least in- 
timation of danger. But many are also armed with weapons 
of defense, such as the spines connected with the fins of the dog- 
fish and the catfish. The mucus which flows over the spines 
is somewhat poisonous, making the wound painful. The 
^'Scorpanoids" have a little poison sac on each side near the tip 
from which the poison flows down a groove of the spine into the 
wound. The Thallassophryne has, besides the dorsal hollow 
poisonous spines, in which the poison sac is situated at the base, 
non-poisonous spines on the gill-covers. The porcupine-fish 
(Di'odon macula'ta) and the globe-fish {Chylomyc'terus geome'tri- 
cus) have spines all over the body. The "surgeons" and rays 

1 Baskett. 



PISCES 



205 



have spines on the tail. The thresher-shark {Alo'pias vulpes) 
has its phable tail prolonged into a terrible weapon, with which, 
it is said, it can kill a whale. This lashing tail serves a second 
purpose by so frightening the small fishes that they crowd to- 
gether and are thus easily obtained for food. The "devil-fish" 
strikes terrible blows with its broad pectoral fins. The saw-fish 




Fig. 165. — Sword-fish (Tetraptu'rus) , yellow-fin tuna, and yellow tail, 
caught with rod and reel at Santa Catalina Island. (Bulletin of B. of F., 
vol. xxviii, 1908.) 



(Fig. 164), sword-fish (Fig. 165), and the like use their long 
strong jaws as frightful weapons. The torpedo and other 
electrical fishes surprise and stun their victims by an electric 
shock. 

Influence of Temperature. — Species differ in their ability to 
endure cold or heat. The brook trout loves the cool water of 



206 BRANCH CHORDATA 

the mountain streams, while the catfish can Hve in exceedingly 
warm water. "Fishes have been found in hot springs of 120° F." 
The Protop'terus of Africa and Asia "so completely slimes a ball 
of mud around it that it may live thus for more than one season."^ 
Other fishes bury themselves in the mud and wstivate through 
the dry season. The little "mud-skippers" move from pond to 
pond by the use of their pectoral fins. Other fishes migrate to 
cooler waters as necessity requires. In winter some of the 
fishes of our small streams hibernate in the mud, while some, 
as the carp, may have the water frozen into ice about them and 
live when thawed out. 

Development. — The sexes are separate. Multiplication is 
by eggs, which are numerous. The cod is said to lay one 
million eggs. In the bony fishes the eggs are naked and numer- 
ous, and fertilization usually takes place in the water. 

In sharks the eggs are few and are protected by a horny shell. 
In most sharks and in a few bony fishes the eggs are fertilized 
and hatched within the body of the mother fish. Mating takes 
place in a few viviparous forms only. Most fishes do not care 
for their young "fry," but the stickleback builds a nest and de- 
fends it with great courage. There is usually no metamorphosis, 
but some ocean species change almost as much as frogs. 

SUB-CLASS I. ELASMOBRAN'CHII 

The rays and sharks represent the Sela'chil, in which are found 
all the living elasmobranchs. They have no operculum (gill- 
cover) and no air-bladder. The skeleton is cartilaginous. The 
mouth and nostrils are ventral and the tail heterocercal.^ 
The scales are small. "The cloaca is the common outlet for the 
rectum, renal and reproductive ducts." Some are viviparous, 
others lay a few eggs, each enclosed in a chitinous case. 

Sharks vary in length from 2 to 60 feet, the majority being 
under 8 feet in length. Some are large and voracious, a few 
dangerous even to man. Hornaday says the only loss of life 
from sharks on our coast occurred in 1830. They feed mostly 
upon fishes. 

The rays {Rai'idce) have the body disk shaped, broad, and flat, 

1 Baskett. 2 Glossary. 



HOLOCEPHALI 



207 



the pectoral fins being much expanded. The skin is roughened 
by spines or prickles. Rays most generally live on the bottom of 
the sea, feeding upon fishes, 
mollusks, crabs, and other bot- 
tom-frequenting animals. 

To the order Sela'chii belong 
the skates (Fig. 166), sting-rays, 
and torpedoes or electric-rays. 
The saw-fish ray also belongs 
to this order. Its formidable, 
sharp-toothed snout, several 
feet in length, makes it a 
dreaded enemy. It disables 
its prey by dashing into a 
school of fishes, striking right 
and left. Then it eats its dis- 
abled prey at leisure. 

SUB-CLASS II. HOLOCEPH'ALI 

This group is represented 
on our Atlantic coast by the 
Chimm'ra monstro'sa (Fig. 167). 

The Holoceph' all were formerly abundant, but are now repre- 
sented by only a few genera. The skeleton is cartilaginous and 
the skin is smooth. These are very peculiar looking fishes, as a 
glance at Fig. 167 will show. The nostrils and mouth are ven- 




Fig. 166.- 



Common skate {Ra'ia 
erinacea.) 




Fig. 167. — Chimoe'ra monstro'sa. (Claus.) 

tral. In general they resemble the sharks in their compressed 
form, but differ from them by the large head and small mouth. 
"Fossil remains are found from the lower Jurassic rocks upward." 



208 



BRANCH CHORDATA 
SUB-CLASS III. DIP'NOI 



The "lung fishes" are snake-hke or eel-hke (Fig. 168), and 
bear small, soft, cycloid scales, small paired fins, and a diphycer- 




Fig. 168. — Lung fish {Protop'lerus annecferis) . (Boas.) 




Fig. 169. — The Cer'atodus of Queensland, an air-breathing and water- 
breathing mudfish of the ancient type, with paddle fins. (From Baskett, 
" The Story of the Fishes," D. Appleton and Co., Publishers.) 

cal caudal fin. The skeleton is largely cartilage and the noto- 
chord persistent. They live in fresh water, and usually breathe 



TELEOSTOMI 



209 



by gills, but when the water gives out or becomes unfit for use 
the swim-bladder, which may be single or double, is used for 
lungs. It opens into the ventral side of the gullet and contains 
air-cells. In this case the air enters through the nose. 

They are interesting as showing how land forms may have 
originated from aquatic forms. There are only three existing 
genera: the Lepidosi'ren, of the Amazon; the Cer'atodus (Fig. 
169), of Australia, and the Protop'terus, of Africa. The Protop- 
terus (see Fig. 168) "can live out of water, it burrows in the 
mud at the dry season and builds a cocoon lined with mucus in 
which it remains quiescent until the wet season."^ 

SUB-CLASS IV. TELEOS'TOMI 

To this extensive sub-class belong our bony fishes, including 
most of the living fishes. It contains thousands of species. 




Fig. 170. — Remoras and shark, showing dorsal fins modified into sucking 
disks, by which the remora attaches itself to the shark in its commensal Hf e, 
thus securing free transportation. (From Baskett, " The Story of the 
Fishes," D. Appleton and Co., Publishers.) 



Familiar examples are the perch, sunfish, catfish, trout, carp, 
pike, cod, and salmon. The mouth is terminal. The nostrils 
are on the upper surface of the snout. The tail is homocercal 

^ Hertwig. 
14 



210 



BRANCH CHORDATA 



(see Fig. 170, Rem'ora), the scales are either ctenoid or cycloid. 
These fishes vary in shape. They vary in size from our little 
darter, 1^ inches in length, to the ''horse-mackerel," which may 
weigh as much as a cow. They differ in habits from the pre- 
daceous, swift pikes and pickerels to the peculiar flounder on 
the bottom of the sea. 

The Remora (Fig. 170) is a lazy fish. It has a sucker on. 
top of its head, by which it holds fast to sharks or larger fishes, 
and thus saves itself the effort of locomotion. 

Order I. Crossopteryg'ii. — There are only two existing genera, 
Polyp'terus and Calarnoichthys, of Africa. 

Order II. Chondros'tei (Sturgeons) (Fig. 171). — They have 
paired fins with no basal lobe, supported by dermal rays. The 
pelvic fins are abdominal. The vertebral column consists of the 
notochord with cartilaginous arches. The tail is heterocercal. 




Fig. 171. — Common sturgeon {Acipen'ser stu'rio). (Report U. S. F. C, 

1899.) 



The mouth is ventral, projectile, and toothless, and sucks up 
worms and larvae from the muddy bottom. The surface is 
roughened by separate scales and by five rows of bony plates. 

Sturgeons are found in streams and lakes of the Northern 
Hemisphere and are the largest fresh- water fishes. Those of the 
lower Columbia River sometimes weigh from 800 to a 1000 
pounds. 

From the swim-bladder of the sturgeon, glue, cement, court- 
plaster, and isinglass are made. The egg-masses, called roe, 
furnish caviare. 

Order III. Holos'tei. — Familiar examples of this order are the 
gar-pike and the mud-fish, often called dog-fish, of the streams 
of the central states. 

The skull is ossified. The scales are ganoid or cycloid; the 
tail, diphycercal or homocercal. The pelvic fins are abdominal. 



TELEOSTOMI 



211 



The spiral valve is present. The double air-bladder aids in 
breathing. 

The gar-pike (Fig. 172) has a cylindric body covered by 
rhomboid, bony scales, which are coated with enamel. The 
snout is long and bony and armed with sharp teeth. This fish 
is voracious. There are three species found in the fresh water of 
North and Central America, including Cuba. They are from 
5 to 10 feet in length. 




Fig. 172. — Gar-pike {Lepidos'teus os'seus). (After Tenney.) 



The mud-fish or bow-fin is abundant in the shallow waters of 
the Mississippi Valley. It has a somewhat bony skeleton and a 
soft flesh, which is not generally used as food. 

Both the gar-pike and the bow-fin come to the surface to emit 
gases and to take in a fresh supply of air. They can live some 
time out of water, when they use the air-bladder as a sort of 
lung. 





Fig. 173. — Cycloid scale. 



Fig. 174. — Ctenoid scale. 



The three foregoing orders are often spoken of as Ganoids. 
Though now insignificant, they were abundant in the Paleozoic 
and Mesozoic Epochs. 

Order IV. Teleos'tei. — The skeleton is well ossified. The tail 
is usually homocercal. There is no spiral valve save in one 
genus. The scales are cycloid or ctenoid (Figs. 173, 174), or, 
in rare instances, the body is naked. The operculum is always 



212 BRANCH CHORDATA 

present. The swim-bladder is usually present, but its duct is 
often closed. Eyes are usually conspicuous and without hds. 

Reproduction is by eggs. They are small and numerous, 
and are fertihzed in the water by the milt deposited by 
the male at the same time. This accounts for the enormous 
schools of some fishes in certain places at the breeding season 
each year. They sometimes go thousands of miles to reach these 
spawning places. The salmon come from the salt water up 
into the rivers to deposit their eggs, which are about the size 
of peas, in depressions or nests. When very small the young 
salmon are banded and called parr, and later become silvery 
smolt. The perches form nests or hollows in the ground near 
the shore. In a form allied to the perch both male and 
female form these depressions and guard the eggs. The male 
Chromis of Lake Tiberias carries the eggs and young in its 
mouth. The stickleback (see Fig. 163), a small fresh-water 
fish, builds a nest and the male cares for the young. The 
male Loph'ohranch carries the eggs in a ventral pouch, forcing 
the young out by pressing the pouch against a stone. An 
Indian ocean form carries the eggs in a pouch formed by the 
ventral fins of the mother. 

Sub-order Physos'tomi includes the catfishes, buffalo, carp, 
salmon, trout, herring, eels, etc. 



The catfishes (Sihi'ridce) are devoid of scales. The majority live in 
fresh water. The head is flat and the wide mouth is provided with long 
thread-like feelers or barbels. They have, for a weapon of defense, a strong 
stiff spine for the first ray of dorsal and pectoral fins. They are sluggish 
and abound in the muddy streams of the Mississippi Valley. The flesh is 
quite free from bones and is much used for food. Some catfishes weigh 
150 pounds. 

The common catfish guards its young. The South American catfish 
carries its eggs and young in its mouth. Other South American species 
build nests of leaves in which they place their young. An electric catfish 
inhabits the Nile, and blind catfishes live in subterranean streams of Penn- 
sylvania. 

Carps, buffalo fishes, and suckers have a naked head and usually scaly 
body. The flesh is bony and not of much food value, yet quite largely used 
because inexpensive on account of the immense number seined. They have 
a toothless sucking mouth and are vegetable feeders, hence the intestine 
is long. The air-bladder consists of two or three links. . . . The 
shiners, minnows, and dace (Fig. 175) belong to this group. The black- 
nosed dace {Rhlnich'thys atronasus) is a nest builder. Both male and 
female form a depression in which the eggs are deposited. Both parents 



TELEOSTOMI 



213 



then cover them by a heap of stones placed layer upon layer to a height 
of about 10 inches. 

The salmon {Salmon' id(E) are found in Europe and North America. 
They live in salt water, but often go thousands of miles to their fresh-water 




Fig. 175. — Showing longitudinal section of the nest of a dace with the 
male and female fish in the nest. The stream flows in the direction indi- 
cated by the arrow at the upper left-hand corner of the figure. (Bull. 
Bureau of Fisheries, 1908.) 

breeding places. The white fish and the various species of fresh-water 
trout belong to this group and are delicious food fishes. The red-spotted 
brook trout is most widely known, and is found from Maine to Dakota. 
On account of its great cunning the trout is much sought by sportsmen, and 
is fast becoming exterminated in its natural haunts. 




Fig. 176.— Eel {Anguil'la chrysypa). (Bull. U. S. F. C, 1895.) 



Eels (Anguil'lidce) have the body greatly elongated, having many ver- 
tebrae, and being almost cylindric (Fig. 176). They have no ventral fins 
and the " pharyngeal and opercular bones are more or less deficient." 
The scales are minute or entirely wanting and the skin is very slimy. They 



214 



BRANCH CHORDATA 



are mostly tropical and marine. The true eels, genus Anguilla, which 
crawl " in the mud and ooze of brackish and fresh waters of most regions, 
are absent on the Pacific Coast of America."^ They are very voracious 
and are especially fond of shrimp and crayfish, which they find by over- 
turning stones. They will also devour dead fish. They sometimes go 
considerable distances in the damp vegetation on land, thus avoiding water- 
falls and other obstructions. The females are larger and lighter colored 
than the males and have smaller eyes and higher fins. In the spring the 
eggs are deposited iu the sea. It is said the young ascend rivers and after 
two or three years return to the sea to spawn. A Brazilian eel {Gymno'tus) 
is electric, having two pairs of batteries in the ventral portion of its long 
tail. " A metamorphosis is known only in the eel-like fishes, the larvae 
of which are flat, transparent forms, with colorless blood, enormous tails, 
and very small trunks. The larvae normally occur m the sea at a depth 
of several hundred fathoms. "- 




Fig. 177. — Winter floimder (Pseu'dopleuronec'tes america'nus). 

Goode.) 



(After 



The blind fishes {Amhlyop'sida-) of Mammoth Cave are colorless and 
translucent. They have rudimentary eyes, but have lost their sight 
through disuse for many generations. They have no lateral line. Their 
knowledge of danger comes through the hearing, which is very acute. The 
head is very flat and the mouth is directed upward, as food is scarce near 
the bottom. They come to the surface to feed, but at the slightest noise 
dart beneath stones at the bottom. 

Sub-order Anacan'thini includes the cod, haddock, whiting, as well as the 
flat fishes — soles, turbots, flounders, halilDuts, etc. There are nearly a 
himdred species of codfish. Some reach a length of 4 or 5 feet and weigh 
100 pounds. The female lays nine or ten millions of eggs in a single season. 
They rise to the surface of the sea and hatch in about twenty days. 
There is one fresh-water codfish. 

The haddock resembles the cod in appearance and habits. 



1 Jordan. 

2 Kingsley's translation of Hertwig's 



• Zoology." 



TELEOSTOMI 



215 



Many kinds of flounders lie upon the left side upon the sea bottom. 
The young flounder is somewhat cylindric, has an eye on each side, and 
swims vertically like other fishes. The eye moves over by successive stages 
until both eyes are upon the upper or right side (Fig. 177j. The mouth 
also becomes crooked and the under side of the fish becomes white. The 
upper side is colored and its color may be changed to suit the surroundings. 
'■ The blind flounder does not adapt its color to its surroundings." 

The halibut sometimes attains a weight of 400 pounds and a length of 
6 feet. It is found on both sides of the Atlantic Ocean. 

Sub-order Acanthop'teri. — The spiny-rayed fishes constitute 
a large group, including the greater number of the marine fishes 
and many fresh-water species. The stickleback, perch, mullet, 
mackerel, our river bass and sea bass, and our common sunfish 
belong here. 

The perch is a carnivorous fish found both in fresh water and along the 
seacoast and is widely distributed. These fishes spawn in winter, forming 
nests in the gravel near the shore. 




Fig. 178. — Large-mouthed black bass (Microp'terus salmoides). (Bull. 
U. S. F. C, 1900.) 



The bass and sunfish are common in our streams. The black bass is 
found in clear running water from the St. LaT\Tence to Dakota and south to 
Arkansas (Figs. 178, 179 1. Its length is 1 to 2 feet and it weighs from 2 to 
7 pounds. It varies in color, the adult being olive green. It is a great 
game fish. The sunfishes have short compressed, bodies. They are 
carnivorous, gamy, and usually brightly colored. 

The green sunfish (Lepo'mis cyaneU'us), common in streams east of the 
Mississippi, makes a nest of gravel in the shallow water and deposits several 
thousand eggs, which the male guards. 

The seventy species of mackerel (Scom'bridce) are all marine. In early 
summer gi-eat schools appear on the shores from Greenland south to Cape 
Hatteras. The yoimg from one female number from 500,000 to 600,000. 



216 



BRANCH CHORDATA. 



As they go north after spawning vast numbers are caught, whole fleets 
being engaged in catching them. The mackerel is phosphorescent and the 
light from these enormous schools is so great that they can be seined at 
night. They are sold either fresh or salted. One of the largest and swift- 
est of the mackerel tribe is the sword-fish, in which the upper jaw is de- 
veloped into a long, bony, sword-like projection (see p. 205). This forms a 
strong weapon, as the fish dashes into schools of fishes, cutting and slashing 
and devouring them. It has been known to pierce the wooden and copper 
bottoms of vessels. It does not breed in North America. The young are 
not like the adult. 




Fig. 179. — Small-mouthed black bass (Microp'terus dolomieu). 
U. S. F. C, 1900.) 



(Bull. 



The sticklebacks are found in both North America and Europe. They 
derive their name from their formidable dorsal spines. They are small 
marine or fresh-water fishes. 



Sub-order Pharyngog'nathi includes the Wrasses and "flying- 
fishes." The pectoral fins of flying-fishes (Fig. 180) are large, 
and serve as parachutes when the fishes leap from the water. 

Sub-order Plectog'nathi. — To this group belong the file-fishes, 
which are often protected by plates or spines, and in shape are 
very deep and thin. They are common from Cape Cod to Cuba. 

Here also belong the trunk-fishes, which are enclosed in a 
"box" made up of bony plates or scales, the tail, mouth, and fins 
being movable. 

The porcupine fishes are covered with sharp spines. The 
Gymnodon'ta or "swefl-fishes" can inflate their bodies into spheric 
sacs. Their flesh is poisonous. 

Sub-order Lophobran'chii. — These fishes are covered with 
rings of large plates. They have club-shaped tufted gills, no 



TELEOSTOMI 217 

pelvic fins, and a rudimentary tail fin. The mouth is at the end 
of a long muzzle. 

The pipe-fish resembles the seaweed and has the power of 
changing color to suit its environment. It feeds upon small 
Crustacea and mollusca. It is found on both European and 
American shores. 




Fig. ISO.— Exonautes gilberti. Type. (Bulletin 546, U. S. Fish Commis- 
sion.) 

The sea-horse (Fig. 181) has the muzzle at nearly a right 
angle with the rest of the trunk, giving it a fanciful resemblance 
to the head of a horse. It swims slowly by means of its dorsal 
fins. It wraps its slender curling tail about seaweeds and roots, 
and thus avoids being transported, unless perchance the seaweed 
is floating, when the fish is carried far away from its birthplace. 
It resembles the seaweeds among which it lives — an Austra- 
lian species having reddish streaming filaments resembling 
plants. 

Economic Importance. — Fishes have been of great value since 
primitive times, but the various methods of preserving them by 
drying and canning has greatly added to their importance, for 
they can now be shipped to any part of the world. Probably 
salmon, cod, and herring are of the greatest value. The lake 
and river trout, the white fish, catfish, the black, white, and 
rock bass, and the perches are important fresh-water fishes, 



218 



BRANCH CHORDATA 



though there are scores of others. The value of the annual out- 
put of our streams and coasts is at least $50,000,000. 

Each nation reserves all fishing rights within three miles of its 
coasts. Outside of this the sea fishes are open to the world. 
The largest sea fisheries are those of the Atlantic coast of the 
United States, Canada, and Newfoundland, and next in import- 
ance are those of northern Europe. Thousands of fishermen 
from the United States, Canada, and France are engaged in the 

cod-fishing on the foggy banks 
of Newfoundland, whose shallow 
waters furnish an abundance of 
food for the cod, and make these 
the greatest cod-fisheries in the 
world. The fisheries along our 
New England coast supply most 
of the fresh cod-fish for our home 
use. Gloucester is the largest 
fishing port of the United States 
and supphes a large part of the 
salted cod-fish for our use. "The 
Columbia and other rivers of our 
northwest coast, including Alaska, 
furnish our largest salmon fisher- 
ies. The salmon canning industry 
of Alaska is said to be the largest 
of the world." 

The demand for this whole- 
some food product, together with 
recklessness, has caused the de- 
struction of certain species in 
many waters. To prevent their extermination the United 
States Government has a Bureau of Fisheries which has es- 
tablished fish-hatcheries in almost all the states.- In these the 
spawn are cared for until they hatch, and when old enough the 
young fishes are shipped to various localities for stocking ponds 
and streams; or, the eggs themselves may be distributed. The 
food supply of these fishes is also protected or introduced, and 
their enemies, diseases, and life histories are studied. The 
annual distribution of eggs and young fishes numbers more than 




Fig. 181. — Sea-horse {Hippo- 
cam' pus harhouri). (Bull. U. S. 
F. C, 1907.) 



TELEOSTOMI 219 

a billion and a half. Efforts are made to rid the streams of 
voracious fishes, such as the pike, pickerel, and muscalonge, 
which feed upon our food fishes. 

Besides being used for food, fishes furnish other useful prod- 
ucts. The skin of the "dog-fish" (shark) is used as leather, and 
shagreen. The bodies are used as guano or fertilizer. Oil is 
obtained from the menhaden, cod, and other forms. Caviare 
is a preparation of the salted roe of sturgeons, the preparation of 
which constitutes an important industry on the Black and Cas- 
pian Seas. Scales of some species are used in ornamental work, 
and the teeth of sharks are used as weapons by Pacific Islanders. 
The swim-bladders of cod-fishes are used in making isinglass. 
They are also pickled and eaten under the name of "sounds." 

Geologic Distribution. — Teeth of the true fishes have been 
found in the Ordovician of Europe. The remains of sharks prove 
their existence in the Silurian. Fishes are found in great variety 
and abundance in the Devonian Period, the sharks, lung-fishes, 
Crossopterygii and the Ganoids, the most advanced, are repre- 
sented. The bony fishes (Teleosts) are entirely absent in the 
Devonian. These, according to Scott, are approximated by 
some of the Jurassic fishes. In the Cretaceous Period, Ganoids 
become rare and Teleosts take the dominant place among fishes. 
Marine and fresh-water fishes assume the modern forms in the 
Eocene Epoch. 

Important Biologic Facts. — The skull is a continuation of 
the vertebral column, and contains, but is not filled, by a genu- 
ine brain. The vertebrae are amphicoelous, that is, concave at 
each end. The true fishes have true jaws. 

They have a closed, though an incomplete circulation. 
The blood-corpuscles are red. 

The multiplication is sexual, but the eggs, or roe, are ferti- 
lized in the water. 

The skin of vertebrates is distinguished from that of inverte- 
brates by the many layered condition of the epidermis and the 
thickness of the dermis. The scales of fishes are of dermal origin 
and different from the epidermal scales of reptiles. It is 
from the dermal scales that the bony plates of turtles and 
armadillos have arisen, as well as the secondary or membrane 
bones. 



220 



BRANCH CHORDATA 



The strange development or change of the flounder from a sym- 
metric to a "flat" fish demonstrates the principle that special 
habits of life result in special modifications of structure which 
fit the animal for those habits. 

The lung-fishes (Dipnoi) show many advancements toward 
the air-breathing conditions, such as the swim-bladder used as 
a lung and the partly separated auricle, and the flipper with a 
central axis rather than a fin, so that zoologists are led to be- 
lieve that they may represent the division of fishes from which 
the amphibians sprang. 

Classification. — 



Sub-phylum Vertebrata or Craniata. 



Class I. Cyclostom'ata. 

Order I. Petromyzon'tes. 
Order II. Myxinoi'dei. 

Class II. Pis'ces. 

Sub-class I. Elasmobran'chii. 
Order I. Cladosela'chea. 

Order II. Pleuracan'thea. 
Order III. Sela'chii. 



Sub-class II. Holoceph'ali. 

Sub-class III. Dip'noi. 

Order I. Monopneu'mona. 
Order II. Dipneu'mona. 

Sub-class IV. Teleos'tomi. 

Order I. Crossopteryg'ii. 
Order II. Chondros'tei. 
Order III. Holos'tei. 
Order IV. Teleos'tei. 



Lamprey, hag-fishes. 

Lamprey. 

Hag-fishes. 



Extinct shark-like forms. 

Cladoselache. 
Extinct Pleuracanths. 
Extinct forms and all the 

living Elasmobranchs, 

as sharks and rays. 
Three genera of Chimce- 

ridce. 

Ceratodus. 

Protopterus and Lepidosi- 
ren. 



AMPHIBIA 



221 



CLASS III. AMPHIBIA 

To this class belong the toads, frogs, salalmanders, and 
newts. The skin is smooth, as in the frog, or warty, as in the 
toad, with a glandular secretion. "One group, however, possesses 
minute scales, but some of the extinct Amphibia were provided 
with well-developed bony plates in the 
integument." — Weysse. It is often 
highly colored owing to the pigment 
cells in the deep layers. In the com- 
mon ''tree-toad," as well as in some of 
the terrestrial frogs, the color may be 
changed to harmonize with the en- 
vironment. No amphibians are ma- 
rine. Most of them are aquatic or 
semi-aquatic. In the adult stage some 






Fig. 182.— Bullfrog. (Skeleton 
cleaned and mounted by stu- 
dents.) 



Fig. 183.^ Nedurus. (Skeleton 
cleaned and mounted by stu- 
dents.) 



are terrestrial, some arboreal. They are usually carnivorous in 
the adult stage, but the larvae may be herbivorous. They hiber- 
nate in the mud at the bottom of a stream and may hve a long 
time without food. They make fine specimens for study in a tank 
or tub, since many of them will endure captivity a good while. 



222 



BRANCH CHORDATA 




Fig. 184. — Anatomy of common frog: My, mylohyoid; sr, sternoradials ; 
th, thyroid; lu, lungs; /, fat-body; Te, testis; St, stomach; Sp, spleen; R, 
rectum; a, adductor longus; toi^i, vastus internus ; ms, sartorius; n', rectus 
internus major; ta, tibialis anticus; g, gastrocnemius; n", rectus internus 
minor; a", adductor magnus; rab, rectus abdominalis; B, bladder; vd, vas 
deferens; b, gall-bladder; Ki, kidney; pv, portal vein; Li, liver; V, vena 
cava inferior; Ao, aorta; S, vocal sac or croaking-bag. II. Origin of the 
arterial trunks: I, Arteria ingualis; eg, carotid gland, which is merely a 
rete mirabile; cr, carotid artery; Ao, aortic arch; Pa, pulmonary artery. 
III. Dorsal view of muscles of hind leg: gl,_ Gluteus; ra. rectus anterior; 
p, pyriformis; ve, vastus externus; S7n, semimembranosus; b, 6, biceps; g, 
gastrocnemius; per, peroneus. (From drawing by C. S. Minot.) (From 
Packard's "Zoology," Henry Holt & Co., Publishers.) 



AMPHIBIA 223 

The Skeleton. — There are two occipital condyles. The ver- 
tebrae of the lower forms are like those of fishes, biconcave; 
those of higher Amphibia are usually concavoconvex. A 
sternum first appears in this class, as well as a typical vertebrate 
limb-skeleton. The pelvic girdle is united with the spinal col- 
umn. There may be four, two, or no limbs, that take the place 
of fins. They have digits which are generally without claws.^ 
The tail is temporary in frogs and toads and permanent in 
other amphibians. Teeth are present in most amphibians, but 
lacking in the toad. They are small, sharp, and point back- 
ward. 

Respiration. — Amphibians breathe by gills in the larval or 
tadpole stage, and in the adult forms by persistent gills or by 
persistent gills and lungs, as in Necturus, or by lungs, as in the 
salamander. The skin is also an important organ for taking in 
oxygen and giving off impurities. The frog breathes with the 
mouth shut, by lowering the tongue and taking in air through 
the nostrils, then raising the tongue, closing the nostrils, and 
forcing the air into the lungs. 

Circulation (Fig. 184). — Amphibians are poikilothermal. The 
heart has one ventricle and two auricles. The arteries carry the 
blood to all parts of the body. The veins from the lungs return 
the pure blood to the left auricle, and those from the body return 
the impure blood to the right auricle. The auricles contract 
and force both pure and impure blood into the ventricle, which 
forces it out in such a manner that the venous blood goes to the 
body and the pure blood to the head.^ 

The Nervous System (Fig. 185).— The brain of a frog has 
advanced above that of the fish in the development of the cere- 
brum, but the cerebellum, which is very small, being, in fact, 
but a thin lamella, is inferior to that of the fish. 

The skin on the whole surface of the body is provided with 
tactile nerve-endings, and contains numerous glands which 
keep it moist while out of the water. Special taste organs are 
located on the tongue and mouth. In adult amphibians the 
nostrils open into the mouth, and Baskett says, "there is much in 
the arrangement of the mucous membrane of the frog's nose 
which implies that it smells." The strong bdors of some of their 

1 See "Amphibia and Reptiles," Gadow, p. 146. 

2 Linville and Kelly's "General Zoology," p. 330. 



224 



BRANCH CHORDATA. 



excretions would also imply a sense of smell, but these may be 
wholly for defense. The nostrils^ of toads and frogs can be 

closed by special muscles. 

The lateral line of the tad- 
pole disappears in the adult. It 
seems that whatever senses may 
be located in the lateral line, 
they are ineffectual outside of 
water. 

In most amphibians there is 
an internal ear which opens by 
one or two openings into the 
mouth, back of the openings 
from the nostrils. None of them 
have any outside opening to the 
ear, but most of the higher forms 
(Anura) have a drum-cavity and 
a tympanic membrane over it, 
lying at the surface. A single 
bone, the columella, lies across 
the middle ear and has one 
end against the tympanum. 
There is no cochlea, or at least a 
very rudimentary one; hence it 
does not seem possible that the 
frog can detect differences in 
pitch. Perhaps this accounts for 
his monotonous song. Yerkes 
found that frogs "straightened 
up and raised the head as if list- 
ening when other frogs croaked 
or splashed into the water," but 
found it impossible to make them 
respond in any way to any noise 
he himself made so long as he 
remained in visible. ^ He thinks 
they depend on sight for the 




Fig. 185. — Brain and spinal cord 
of frog (x about 2) : a, Cerebral 
hemisphere; b, olfactory lobe; c, 
eye; d, thalamencephalon ; e, optic 
lobes; f, cerebellum; g, medulla 
oblongata; h, fourth ventricle; i, 
spinal cord; I, Olfactory nerves; 
II, optic nerve; III, oculomotor 
nerve; IV, patheticus; V, fifth 
nerve; VII, facial nerve; VIII, 
auditory nerve ; IX, glossopharyn- 
geal nerve; X, vagus nerve; 1-10, 
first to tenth spinal nerves; 2 and 
3 unite to form the brachial, and 
7, 8, and 9, to form the sciatic 
plexus. (Shipley and McBride.) 



1" There seems to be no experimental proof of specific taste or smell 
among amphibians or reptiles." — Washburn. ^ Linville and Kelly. 



AMPHIBIA 225 

knowledge of danger. Romanes records an instance of a pet 
frog which would come when his name, "Tommy," was called, 
no matter at what time of day, though fed only at morning, and 
another instance of a toad kept as a pet for thirty-six years, 
which knew all of his friends. In either case, the knowledge 
might have been gained, at least in part, by sight. 

The eye has no lids in the lower forms, and is degenerate in 
the Pro'teus, which lives in caves (see Fig. 189), and in some 
Gymnophi'ona. Most of the Anura have an upper lid, but no 
lower one. There are no tears. The "flying tree-toad" has 
large owl-like eyes (see Fig. 195), so that it can see as I'ar as it 
leaps. Frogs are able to project the eyes upward to give greater 
range of vision. When the mouth is inflated the eyes are pushed 
forward, since there is no partition between the eyes and mouth. 
It is well known by boys that frogs recognize bright colors, and 
it has been proved by experiment that they can distinguish red 
from white. 

Development. — The eggs of Anura, which consist of the 
yolk enclosed in a mass of jelly-like matter, are not surrounded 
by a shell. They are usualy deposited in masses (frogs) or in 
strings (toads), and then left to hatch by the heat of the sun. 
The little tadpole has a small sucking mouth and a slender active 
tail. The branched gills soon grow out on the sides of the neck, 
but are later replaced by internal gills, when the water passes 
in through an opening on each side of the neck. The tail is 
gradually absorbed, the legs develop, the holes on the sides of the 
neck close, and the hmbs develop underneath the skin, the hind 
legs coming out first in the frog forms, but in all others it is the 
fore limb that first shows.^ Meanwhile "the tadpole ceases to 
feed, the whole intestinal canal is voided of its contents, and, by 
histolysis, is entirely rebuilt, becoming wider and shrinking 
to about one-sixth of its original length, undoing thereby the 
spiral, preparatory for the coarser food, which consists of in- 
sects, worms,"^ and any live animals it can capture. 

Care of the Young. — Usually the parents take no care of the 
young, but there are some interesting exceptions. The little 
South American frog (Rhinoder'ma dar'wini) carries the eggs in 

' Baskett, " Story of the Amphibians and Reptiles," p. 34. 
2 Gadow, p. 61. 

15 



226 



BRANCH CHORDATA 



the immense vocal sacs of the male until they are hatched. A 
tree frog ( Hylo'des linia'tus) of Dutch Guiana carries its young, 
which cling by sucking disks, upon its back. The "Surinam 
toad" (Fig. 186) places the eggs upon the back of the female, 
where the skin is soft and spongy, during the breeding season. 
Each egg sinks down and is covered by a jelly-like film. They 
remain embedded here until the tadpole stage is passed. The 
pouched frog ( Nototre'ma mar swpia' turn) has the eggs stored in a 
pouch on the back, where they hatch and the larvae develop. 
The male of the European species {A'lytes ohstet'ricans) winds the 




Fig. 186. — Surinam toad, showing young escaping. (From Holder's 
" Elements of Zoology," American Book Co., Publishers.) 



string of eggs about the thighs and body. A Japanese frog 
makes a nest on the ground. One in Brazil makes circular nests 
in shallow water, smoothing and shaping rings of mud and laying 
the eggs in these cup-like depressions. Many amphibians are 
viviparous.^ 

Defense. — Almost all amphibians are more or less poisonous, 
says Gadow. It has been proved that if a quantity proportion- 
ate to the size of the animal be injected, that the poison secreted 
by toads, salamanders, and newts will kill mammals, birds, rep- 
tiles, and fishes. The poison acts upon the heart and central 
1 Baskett, see " Viviparous Amphibians." 



AMPHIBIA 227 

nervous system. ^ The Indians of Columbia, it is said, use the 
secretion of Dendrob'ates tincto'rius for poisoning arrows to shoot 
monkeys. That this secretion protects these amphibians from 
their enemies (the "glass snake" is an exception) is evident from 
the fact that "a dog that has once been induced to bite a toad 
suffers so severely that it will not repeat the experiment." The 
handling of the tree-frogs irritates both nose and eyes. Many 
of the most poisonous amphibians (as Salaman'dra macuWsa, 
Bom'hinator , and Dendrob'ates) are conspicuously marked with 
yellow and black. The horned frog of South America, which 
fights and poisons its antagonist, is brilliant in green and gold. 
Many assume a threatening attitude. " Toads normally have 
the sections of the breast-bones overlapping, so that they can 
swell themselves enormously when angry. "^ 

Ec'dysis. — All amphibians shed the epidermis. The first 
ecdysis occurs at the time the metamorphosis is completed, 
preparatory to terrestrial life. The Anu'ra roll up the cast-off 
skin and swallow it. The Urode'la also eat it. The skin of the 
Anura generally splits down the back, but that of the Urodela 
breaks loose around the mouth, and the animal slips out, turn- 
ing its hide wrong side out. So long as growth continues, the 
skin must be shed often, as this outside layer will not ''give" 
to make room for growth. The adult Urodela do not molt 
often, but usually at the breeding season, when they go to the 
water to deposit their eggs. The Anura molt frequently, at 
least every few months, probably to keep the skin moist. 

Voice. — Most of the Anura and some of the Urodela have a 
voice produced by the larynx, which is often provided with a 
complicated cartilaginous and muscular apparatus and with 
vocal cords. The female of the Anura is mute or utters only a 
grunt. The sound made by the male is called a croak. The 
voice of Urodela is a feeble squeak. The song of frogs and toads 
is usually of the nature of a serenade to its would-be mate, for 
they do not, as a rule, cry out in fright nor in rage. A notable 
exception is that of the vicious horned frog of South America, 
which is said to defy its foes with a sort of bark, but which has a 
clear bell-like tone for its friends. Our common green frog is 

1 Gadow, " Amphibia and Reptiles," p. 38. 

2 Baskett, p. 29. 



228 BRANCH CHORDATA 

also an exception. That cloudy or damp weather has some 
effect in making certain species, as the tree-frogs, sing, is per- 
haps explained by the fact that the skin of amphibians is used as 
a breathing organ as well as for a body covering, and it must be 
kept moist to be serviceable. 

Influence of Temperature. — Amphibians living in the water 
assume its temperature, which varies much from noon to mid- 
night, and from the stream in open sunshine to the cool, shady . 
spring. According to Gadow, "most Anura die when their tem- 
perature rises to 40° C," but those outside of water in open air 
endure greater heat than aquatic ones, since the evaporation of 
the moisture from their skin lowers their temperature. Most 
of them, and especially the drier skinned toads, seek the cool 
shade or even estivate during the hottest part of the summer. 
Many of them, unless they are used to tropical climates, can en- 
dure a very great amount of cold, their temperature sometimes 
falling to the freezing-point during hibernation. Our spotted sal- 
amander, in a jar of water out-doors, was forgotten one severely 
cold night, when the water about it froze soHd. It was put into 
a cool room and allowed to thaw gradually as the weather moder- 
ated, after which the salamander seemed to be as active as ever. 
Of course, the animal was not sawed into parts to find out if 
it was frozen solid, but it surely looked solid enough. It does not 
seem possible that the heart was absolutely frozen, for the heart 
"must not itself be frozen if the animal is to have a chance of 
recovery."^ 

CLASSIFICATION OF AMPHIBIA 

Order I. Stegoceph'ala. — This is an extinct order of amphibians, 
described by Scott as animals, which have a skull "well covered 
with a roof of sculptured bones and which are of moderate or 
small size, not exceeding 7 or 8 feet in length and mostly much 
smaller. The backbone is not ossified, the limbs are weak, the 
tail short and broad, and in many forms the belly is protected 
by an armor of bony scutes. "^ Most of them were like sal- 
amanders in shape, but some were long and snake-like. 

Order II. Ap'oda or Gymnophi'ona. — This group comprises 
one family of limbless, tailless, vermiform, subterranean am- 

1 Gadow, p. 68. 

2 Scott, " Introduction to Geology," p. 427. 



CLASSIFICATION OF AMPHIBIA 



229 



phibians of the tropical regions which burrow in the ground and 
feed on worms and insect larvae. They have from two hundred 
to three hundred vertebrae. There are no gills or gill-sHts in the 
adult stage. Their mode of locomotion is much like that of the 
earthworm. It is produced by the peristaltic motion of the 
skin, aided by the numerous ring-shaped constrictions. The 
eyes are vestigial and concealed beneath the skin. 

The only family is CcBcili'idoe, with some forty species. Some genera, 
as Ichthyophis, have small scales embedded in the skin. Others, as the 
Typhlonectes of Guiana and Venezuela, are scaleless. T. compressicauda 
is 18 inches long and f inch in diameter. Its color is from an olive brown to 
black, which is the general color of most species. Some, as Ichthyophis, are 
oviparous; others, as Dermophis, are viviparous. 



Order III. Urode'la or Cauda' ta. — These are the tailed and 
limbed amphibians. They have four limbs, as in the toads and 




Fig. 187. — Siren (Si'ren lacerti'na). (Chapin and Rettger, Englehard & 
Co., Publishers.) 

frogs; or two, as in the Siren. The skin is smooth and slimy. 
Locomotion is accomplished mostly by body motion, aided by 
the weak limbs, in strong contrast with the limb-motion of the 
frogs and toads. They are not very common as compared with 
frogs and toads. Newts and salamanders are examples. 

Siren'idoe is a small family of two genera of one species each. The 
"mud-eel" {Siren lacertina) (Fig. 187) of the southern United States is 2 or 
3 feet long. Posterior limbs are wanting, and the weak anterior limbs have 
four digits. The tail is long, compressed, and thin. There are three pairs 
of gills, but they atrophy in the young and are redeveloped subsequently. ^ 
The mud-eel is a harmless creature, burrowing in the mud of ponds and 
ditches. Dorsally it is dark colored, but lighter ventrally. Sometimes 

1 Gadow, p. 136. 



230 



BRANCH CHORDATA 



it is spotted with small white specks. When swimming, the hmbs are folded 
back. 

The other species {Pseudobran'chus stria'tus) is only about 7 inches in 
length and has three digits to each fore foot. 




Fig. 188. — Mud-puppy. (Chapin and Rettger, Englehard & Co., Pub- 
lishers.) 

The family Prote'idce consists of amphibians ha\-ing three pairs of per- 
sistent gills, two pairs of weak limbs with four digits to each one, or the 




Fig. 189 — Pro'teu^ angui nu Luiupt. (,1 loui Dodge s General Zool- 
ogy," American Buok Co., Publishers.) 



anterior pair with two, and the posterior with three digits. The eyes are 
without Hds and covered by a transparent skin, but are functional. They 
have teeth on the vomer, mandible, and premaxillaries. 



CLASSIFICATION OF AMPHIBIA 231 

The water-dog or mud-puppy Fig. 188j ( Xedu'rus macula' tus) is a rather 
common, clumsy form found in the ^lississippi Valley and the region of the 
Great Lakes and east to the Alleghenies. They are nocturnal, but vora- 
cious, feeding on insects, worms, small fish, and crustaceans. Those in 
oiu- laboratory were 15 inches long with dark brown spots. 

The blind Pro' teas angui'nm of Eiu-ope (Fig. 1S9,' belongs to this family. 
It is white and hves in total darkness in a temperature of about 50" F. If 
brought to the light the skin will ultimately change to a dark color. 
There is a similar species {Typhlomol'ge rath'bunii in Texas. 

F amil y Amphiumidae. — These animals are without giUs in the adult 
stage. They have teeth in both jaws. They have foiu- small, weak 
limbs. 

The heUbender >Cryptohran'chus alleghanieji'sis) is a stom -bodied, four- 
footed, ugly, but harmless amphibian, which is sometimes 2 feet in length. 
It is brown or gray above and lighter below. It feeds on worms, craj-fish, 
fish, and such other creatures as it can obtain in its aquatic habitat. It is 
restricted in its distribution to the streams of the mountaiaous regions of 
the eastern United States. 




Fig. 190. — Congo snake (Amphiu'ma means). (From Holder's "Elements 
of Zoology-," American Book Co., Publishers.) 

The giant salamander of .Japan (C. japon'icus) reaches a length of 4 to 
5 feet. It lives in small streams and motmtain meadows of .Japan and 
China, from 600 to 4500 feet above sea-level. Sasaki jeports that it hves 
singly, hdng concealed under rocks, in swift, thickly shaded, small, clear, 
cold streams. It feeds on animals which it can capture in the water and 
mav be caught with a fish-hook. It is used for food by the Japanese. 

The "Congo snake" t Amphiu'ma me'ans) (Fig. 190) is eel-like, with 
four weak limbs, having two or three toes each. Its general color is black, 
with hghter under parts. It attains a length of 3 feet. It Uv^ in the 
swamps and rice fields of the southeastern United States. It feeds on 
cra>-fish, moUusks, and fishes. It is quite harmless. 

t2Lm.i\\- Salaman'dridoB, or salamanders and newts, are our most common 
Vrodela. AU are harmless, and are generally but erroneously called 
lizards. They have no persistent gills. They have two pairs of weak 
limbs. Nearly all have movable eyehds and teeth in both jaws. There 
are twelve or fifteen species in the United States. 



232 



BRANCH CHORDATA 



The spotted salamander {Avihlys'toma puncta'tum) is our common species 
in the Mississippi Valley (Fig. 191). It is dark brown or blackish above, 
marked with about thirty irregular yellow spots. It is found in wells and 
cellars. It is oviparous. 

One species {Amhlys' toma tigri'num), which is found in Mexico and Cali- 
fornia and even in New York and Minnesota, affords a striking example of 
neoteny,^ or the " more or less complete retardation of development, or the 
retention of partially larval conditions. "^ If the pond in which this axolotl, 
or larva (Fig. 192), lives begins to dry up, its gills, fins, and tail shrink, and 
finally disappear, the animal begins to breathe air, and gradually becomes a 
terrestrial salamander.^ But if it is reared in deep water or forced by deep 
walls to remain in aquatic conditions, the larval or aquatic gills and tail 
are retained, even after sexual maturity has been reached. One would 
think this was a forcible proof of the influence of environment on the 
development of the individual, but the strangest part of it is that it is said 




Fig. 191. — Common yellow spotted salamander. (Morse.) 

there have sometimes been found, side by side with these prolonged larval 
individuals, others apparently of the same . species which have completed 
their metamorphosis.^ 

The newts or tritons all prefer moisture without heat. In the mating 
season they take to the water, undergo various changes, and become 
aquatic. After the breeding season is over, they become terrestrial, hiding 
in cracks or in the sand. Some estivate in the hot dry season. They 
hibernate usually in the ground, but sometimes in ponds. The food con- 
sists of insects, centipedes, and snails. " They do not drink, but soak them- 
selves in water. "^ 



1 Baskett and Ditmars. 

2 Parker and Haswell. 

3 Linville and Kelly. 

^ Hertwig (p. 587, Kingsley's translation) says adults of true axolotl ar? 
unknown. 

5 Gadow, p. 123. 



CLASSIFICATION OF AMPHIBIA 



233 



The crimson-spotted newt {Tri'ton virides'cens) is abundant in northern 
and eastern states. Above, it is greenish brown, with two rows of crimson 
spots. Below, it is orange, with black dots. It Hves in deeper water than 
is usual for salamanders and " swims freely, often in an upright position, 
with hind legs hanging motionless, while the tail does all the work." 

Order IV. Anu'ra or Ecauda'ta. — "The Anura are a very spe- 
cialized group. Their development (see p. 225) indicates their 




Fig. 192. — Axolotl, a creature living and breeding for generations in the 
water. Amblystoma coming out of the water. Amblystoma breathes by 
lungs, having lost its gills. (From Holder's " Elements of Zoology," 
American Book Co., Publishers.) 



derivation from branchiate, tailed forms, but there is no paleon- 
tologic evidence on this point. "^ 

Aglos'sa. — This group is characterized by the absence of a 
tongue and by a common opening for the Eustachian tubes. It 
is represented by the Pi-pa or ''Surinam toad" of South America 
(see Fig. 186) and by the Dactyl'ethra (Fig. 193) of Africa. 

^Parker and Haswell, p. 291. 



234 



BRANCH CHORDATA 



Phaneroglos'sa. — This group is characterized by the presence 
of a tongue and by distinct Eustachian tubes. It includes the 
toads and frogs. Gadow estimates 900 species in the world. 
Frogs and toads have tails in the larval or tadpole (Fig. 194) 
condition, but are tailless in the adult stage. The body is 
short and stout. They have a small number of trunk vertebrae 
and the caudal vertebrae are replaced by one long bone, the uro- 
style. They have four limbs, the posterior ones, long, strong, and 
adapted for leaping or hopping. Toads are crepuscular and 

nocturnal. They hibernate in the 
mud at the bottom of the water. 
The tadpole or ^'pollywog" is 
fish-like and aquatic. It has a 
long tail and breathes by gills. 
Its intestine is very long, adapt- 
ing it to its vegetable food. 

Family Bufon'idae. — Toads are 
clumsy, stout-bodied, nocturnal insect- 
feeders. The tongue is fixed by the 
anterior end and can be thrust out to 
catch its food. They have no teeth. 
The skin is warty or glandular and 
secretes a fluid for protection. The 
toes are webbed, but not dilated at the 
tips. Toads resemble the ground very 
closely. 

The American toad (Bu'fo lentigino'- 
sus) is familiar to all. The young are 
nearly smooth, the adults warty. They 
are brownish-olive, with a yellowish 
median line and brown spots. There is a bony ridge behind and above 
the eye and two black patches below the eye. The tympanum is large. 

Family Hy'lidae or Tree Frogs. — These are arboreal frogs with an op- 
posing thumb and with adhering disks on the end of each toe, by which 
they cling to the trees in which they live. 

Our most common example is the northern tree-frog ( Hy'la ver'sicolor) of 
the eastern United States and Canada. It is about 2 inches loiig and deli- 
cately colored. " Its color passes within a short time from dark brown or 
olive gray to pale gray or white, occasionally retaining a few large dark 
patches on the back and delicate cross-bars on the limbs." It has small 
warts, which produce an acrid secretion. It is found not over 20 feet from 
the ground in trees or on lichen-covered stone fences. Its color renders 
it almost perfect in protective resemblance. One may be within a foot of 
it and not be able to distinguish it. It croaks noisily in the evening or 
just before a rain. In croaking its vocal sacs swell to enormous pro- 
portions. It remains quiet in the shade during the day, but is lively in 




193. — DaclyVethra capen- 
sis. (Claus.) 



CLASSIFICATION OF AMPHIBIA 



235 




Fig. 194. — The metamorphosis of the frog. The numbers indicate the 
sequence. (Galloway after Brehm.) 




Fig. 195. — Flying tree-toad of Borneo l^Rhacoph'orus). (After Wallace.) 



236 BRANCH CHORDATA 

the evening, feeding on insects. Gadow mentions a tree-frog which Uved 
twenty-one years. 

Faxnily Ran'idae. — Frogs {Ranince) have teeth in the upper jaw. The 
toes, four to five, are more or less webbed. The tongue is hke the toad's. 

Our largest species is the bullfrog {Ra'na catesbia' na) , which measures 
from 5 to 8 inches. It is known by its deep bass voice. It has two 
large internal vocal sacs. Its toes are broadly webbed. In color it is 
varying shades of green above, with faint dark spots, the head is bright 
green, the legs blotched. The tympanum is large. Its hind limbs are 
much prized for food. Bullfrogs are solitary except in the breeding season, 
when hundreds collect in the same small pond. They are commonly found 
sitting half immersed in water, or waiting for their prey upon the banks 
of a pond. The bullfrog is voracious, devouring mollusks, fishes, and frogs, 
as well as ducklings and young water fowls. It is eaten by fishes, birds, 
otters, snakes, and alligators. 

The green frog {R. damata) is a brownish-green color, brighter in front, 
with irregular small black spots, and blotched limbs. Below, the color is 
yellowish white. The tympanum is large. It is common in the eastern 
United States. The vocal sacs are small and internal. 

Wallace describes a species of Ranidoe which was brought to him in 
Borneo. The body was about 4 inches in length and the webs of both fore 
and hind feet were enlarged and used as parachutes by these "flying frogs" 
(Fig. 195). 

Classification. — 

Order. Examples. 

I. Stegoceph'al'ia. Extinct forms. 

II. Ap'oda or Gymnophi'ona. Coeciliidae. 

III. Urode'la or Cauda'ta. Necturus, Salamanders. 

IV. Anu'ra or Ecauda'ta. Frogs, Toads. 



CLASS IV. REPTILIA 

This class of Chordates consists of snakes, lizards, turtles, 
crocodiles, and alligators, together with a number of extinct 
orders. ''Compared with the ages that are gone the reptile life 
upon our globe has decreased to mere parasitic proportions." — 
Ditmars. 

Reptiles are scaly. They are aquatic or terrestrial; a few 
are arboreal. There is one occipital condyle, and the lower jaw 
is united to the base of the skull by a quadrate bone. 

The limbs are four, two (the Python and some kindred forms 
have the vestiges of the hind limbs only), or none, as in the 
"glass snake" and our common snakes. 

Reptiles are poikilothermal. The heart has one ventricle 
and two auricles, except in order Cro'codilia, where the heart has 
two auricles and two ventricles. 



REPTILIA 



237 




Fig. 196. — Illustrations of the nictitating membrane in the various 
animals named, drawn from nature. The letter N. indicates the membrane 
in each case. In man it is called the plica semilunaris, and is represented 
in the two lower drawings under this name. In the case of the shark 
{Galeus) the muscular mechanism is shown as dissected. (Romanes.) 



238 BRANCH CHORDATA 

Reptiles always breathe by lungs. "The air is drawn into 
the lungs of snakes, lizards, and crocodiles by the play of the 
ribs."^ 

The nervous system is somewhat more highly developed than 
in the amphibians. There is a middle and an inner ear. The 
eye has an upper and a lower movable eyelid and also a nicti- 
tating membrane (Fig. 196). True nostrils and salivary glands 
appear first among the reptiles. 

Reptiles are oviparous, ovoviviparous, or viviparous. There 
is no metamorphosis. 

In ecdysis the skin may be cast in one piece, as in all snakes 
save sea-snakes and in most lizards; in strips, as in some lizards; 
in little pieces, as in the western horned toads; or in flakes, as in 
the geckos. Some tortoises shed the whole outer layer of epi- 
dermal shields periodically. 

Gadow briefly defines Reptilia as ''monocondylia with a scaly 
skin." 

Reptiles live longer than most warm-blooded animals. A 
turtle in the Zoological Park, New York, says Ditmars, is esti- 
mated to be over three hundred and fifty years old. 

ORDER I. RHYNCHOCEPHALIA 

Rhynchocephalia is represented by Sphen'don puncta'tum 
(Hatte'ria) of New Zealand. It is a lizard-like, four-limbed, 
pentadactyle, nocturnal, carnivorous reptile | meter in length. 
'Tt is the sole remnant of an order long extinct. It is literally 
a ghost of the past, the oldest surviving type of reptile." — 
Ditmars. 

Its color is dark olive green, with small white or yellowish 
specks on the sides. Its length is from 15 to 30 inches, while 
fossil forms were sometimes 6 feet long. A row of spines extends 
along the back. Its means of defense are biting and scratching. 
It burrows. It lays about ten hard-shelled white eggs in the 
sand. Gadow has "come to the conclusion that they are dull, 
not companionable creatures." Their sound is a grunt or croak. 

For an interesting description of this living fossil read Gadow, 
"Amphibia and Reptiles," pp. 294-300. Look at the picture of 
the skeleton and state the branch, class, and ordinal character- 
istics you see. 

1 Dodge. 



OPHIDIA 



239 



ORDER II. OPHIDIA 

Snakes are considered degenerate lizards, and by some zo- 
ologists are classed with the hzards, and the group together 
called Order Squamata. 

The Ophidians are reptiles with no fore limbs, no pectoral 
girdle, no sternum or sternal ribs, but the ends of the dorsal 
ribs are connected with the ventral scales, or scutes, and both 




fltlOI/ICf/ry^y Hl//0-LtMB& 



A . \iEnT, 

B. koMH TEKKfif/flTiofJ OF 



Fig. 197. — Rudimentary or vestigial hind limbs of python as exhibited 
in the skeleton and on the external surface of the animal {\ natural size). 
(Romanes.) 



scales and ribs aid in the body motion. "A snake literally 
walks on the ends of its ribs." 

Vestiges of the hind limbs (Fig. 197) sometimes appear as httle 
spurs on either side of the vent. The ribs, which begin with the 
second vertebra and continue to the end of the body, aid in res- 
piration. They aid in locomotion also, their ventral ends fitting 
into the "connective tissue of the sides of the ventral transverse 
scales (scutes)." The body is long and the vertebrae very numer- 
ous. 

They vary in size from the enormous ones of the tropics to 
our little green grass snakes. Some are aquatic, some terrestrial 



240 BKANCH CHORDATA 

or subterranean, while still others are arboreal in their habits and 
habitat. 

The color of snakes is usually brownish or green, which affords 
a good protective resemblance to the ground or grass upon which 
they creep. 

The skin is scaly. The horny epidermis is shed from one to 
several times yearly, the whole outer skin, from hps to tail, being 
turned wrong-side out, even to the transparent covering of the 
eyes. The first molting takes place "within forty-eight hours 
after birth" before the young snake begins to feed. In the 
rattlesnake, at each time the skin is shed, "there is left a ridge 
or rim of it at the tail, which forms the rattle." 

Food. — Since there are no limbs for prehension, snakes must 
depend upon the mouth to secure the prey, which is swallowed 
whole. The constrictors, like our common blue racer and the 
boa constrictor, wind their bodies about their victims and 
hterally squeeze them to death. The teeth point toward the 
throat, thus preventing the escape of the prey from the mouth. 
The snake has also a distensible lower jaw, enabling it to swal- 
low an animal as large or larger than the diameter of the snake's 
own body. The bones and palatal apparatus are united by 
ligaments only, thus allowing them to spread apart in the 
process of swallowing. An abundant supply of saliva (which 
appears first in reptiles) renders swallowing the more easy. 

Snakes are carnivorous, feeding upon mice, birds, frogs, and 
insects. Poisonous snakes should be killed, of course, but the 
non-poisonous ones are quite useful in the fields in destroying 
vegetable-feeding animals, especially rodents and insects. 

Respiration is mainly by one lung, the other one being 
rudimentary. The trachea may be slightly protruded between 
the halves of the lower jaw during the process of swallowing, to 
prevent suffocation. 

Senses and Intelligence. — The eyes are not movable nor have 
they a movable eyelid, hence their glassy stare. The lacrimal 
fluid passes internally into the nasal cavities. No external ear 
is visible, though the hearing is good. The sense of smell is 
well developed, some snakes being greatly aided by it in their 
search for prey. The tongue, which is slender, forked, and 
sheathed, is protractile, moist, and very sensitive to touch. 



OPHIDIA 241 

Snakes, while showing considerable intelligence, are seldom 
much attached to their keepers, being more often reticent and 
surly. 

Multiplication. — The eggs of snakes are not hard shelled, 
but are covered with a tough membrane. Generally the snake 
loosely buries the eggs or deposits them half-hidden in cracks 
and crevices. Many snakes are ovoviviparous.^ The young 
are precocial. Male snakes are smaller than the females. 

As in reptiles generally, the number of young at a litter is 
large, but the number varies with the species. That of the 
poisonous snakes is said to seldom exceed fifteen, except those 
of some of the tropical ones. Ditmars mentions a boa con- 
strictor in captivity which " gave birth to sixty-four fully devel- 
oped young, while a huge python deposited seventy-nine eggs, 
which she gathered in her coils and guarded jealously" until 
hatched. During this period of incubation the body tempera- 
ture is raised. Our little garter snake has a litter of about 
thirty-five, v/hile that of the common water snake has been 
known to number sixty. The copperhead has about eight or 
nine young. 

The length of life may be said to be considerably shorter than 
that of the chelonians and crocodilians, as growth is more 
rapid. Adult snakes received in the Zoological Garden, New 
York, says Ditmars, have been kept for ten years without show- 
ing signs of age, and pythons even fifteen years. The snakes 
of this latitude hibernate in caves and dens or in deep crevices 
between the rocks. In the tropical regions some species esti- 
vate in summer. 

Defense. — Besides their protective coloration, snakes are 
further provided with several means of defense. Some are 
protected from their enemies by a characteristic odor, while 
others have the deadly poison fangs. Another, and by far the 
most common means, is by noiseless flight. A few species 
burrow or slip into holes to escape, while the boa constrictors 
squeeze their enemies to death. Most snakes will not attack 
man if unmolested, and they are generally as much frightened 
as the person is. They charm birds, probably by paralyzing 
them with fear, until they can creep up to and catch them. 

^ See Glossary. 
16 



242 



BRANCH CHORDATA 



The author attracted the attention of a charmed bird from its 
gaze upon the snake and the bird immediately flew away. 

The poison gland is an especially modified salivary gland, and 
the poison fangs are maxillary teeth which have a furrow on the 







Fig. 198. — A case of mimicry, where a non-venomous species of snake re- 
sembles a venomous one. (Romanes.) 



anterior side, or the furrow is changed into a canal for the pas- 
sage of the poison to the end of the fang, and hence to the 
deepest portion of the wound, where it poisons the blood of the 
victim. Colton gives, as an antidote, a 10 per cent, solution of 
ammonium carbonate taken internally. 



LACERTILIA 243 

There are many enemies of snakes. Prominent among them 
are kites, hawks, shrikes, and other birds of prey, hogs, and 
man. 

Family Colu^bridse includes all our common harmless snakes, as the 
garter snake, " hoop snake," water snake, green snake, black snake or 
blue racer, blowing viper, and others. They are all perfectly harmless^ 
though they make great pretensions with their terrifying appearance or 
bluff as to what they might do if you came too close. 

Family Crotaridae includes the rattlesnake, copperhead, and water 
moccasin. All of these are poisonous and to be feared. The rattlesnake 
gives warning, not so the deadly copperhead and water moccasin. Hap- 
pily for man, civilization is driving out these dangerous reptiles. 

Family Elap^idse is another family of venomous, chiefly East Indian, 
snakes. There is one species (Fig. 198), the "bead snake" (E^laps fuVvius), 
found from Virginia to Arkansas and south. Jordan describes it as " jet 
black with about seventeen broad crimson rings, each bordered with yellow 
and spotted below with black, a yellow occipital band, tail with yellow 
rings." It is surely an example of warning colors which one will do well 
to heed. A non-venomous species closely resembles it. 

Library References.— Gadow's "Amphibia and Reptiles "—Ophidia. 
Read of snakes of other lands. Baskett and Ditmar's " Story of Am- 
phibians and Reptiles"; Parker and Haswell on "Reptiha"; Ditmars' 
"Reptiles of the World." 

ORDER III. LACERTILIA 

Lizards are reptiles with a distinct head, a snake-hke body, a 
tail generally longer than the body, and four short, nearly 




Fig. 199. — Skeleton of a hzard: sp, Spinous processes, which in the tor- 
toise are flattened into plates; r, ribs; s, shoulder-bone; a, upper arm; e, 
elbow; fa, forearm; h, hip-bone; th, thigh-bone; k, knee; I, bones of the 
leg; q, quadrate bone between upper and lower jaw. (From Holder.) 

equal limbs, or no functional limbs, as in the so-called " glass 
snake " or " joint snake." Their locomotion is aided by a 



244 



BRANCH CHORDATA 



wriggling body motion. " Two aortic, branches, a left and a 
right, survive in lizards."^ 

Lizards are very various in size, shape, color, and habitat. 
Most of them are terrestrial, some burrow, some are semi- 
aquatic, and still others are arboreal. They are generally cov- 
ered with horny epidermal plates^ and shed their skin entire. 

The shoulder girdle and sternum are present. The "flying 
dragons " of the Indo-Malayan countries have "a pair of wing- 




Fig. 200. — Heloder'tnn, a poisonous lizard. (From Holder's "Zoology," 
American Book Co., Publishers.) "The blunt tail of the Gila Monster is 
actually the reservoir for the storage of nourishing fat." — Ditmars' 
"Reptiles of the World." 

like membranes supported by five or six elongated posterior 
ribs, which they use as a parachute or fold up like a fan." 

Food. — Most lizards are insectivorous, eating small animals 
also, but some are herbivorous, living upon buds, blossoms, and 
tender -leaves of plants. 

Special Senses. — The eyes are usually provided with an 
upper and a lower movable eyelid and with a transparent nicti- 
tating membrane. The tympanic membrane is situated in a 
slight depression behind the eye. The tongue is free and both 
jaws are armed with teeth. The mouth is not distensible. 

1 Packard. 



LACERTILIA 



245 



Multiplication. — The egg-laying lizards deposit their eggs 
in the sand or soil, except the Iguanidge, which lay them in hol- 
low trees. Many lizards are viviparous. The male is larger 
and more brightly colored than the female. 

Lizards, as well as amphibians and snakes, find the ocean a 
barrier to their progress, but lizard's eggs have in some way been 
carried to oceanic islands. 

All are harmless except the Gila monster (Fig. 200), of the 
Gila River region, which is the only poisonous lizard known. The 
specimen in our laboratory is about 17 inches long, black, and 
mottled with orange. Its only sound was a hiss, which it gave 
when disturbed. 



1 




Fig. 201. — Glass snake (Opheosau'rus ventral'is). The tail is twice the 
length of the body, and breaks off at the slightest blow. When broken off 
it grows again. (From Baskett and Ditmars, " The Story of the Amphib- 
ians and Reptiles," D. Appleton and Co., Publishers.) 



The Skinks, — This family {Scin'cidce) is represented by the cosmopolitan 
blue-tailed lizard common east of the Rockies as far north as northern 
Indiana, and by the ground hzard of the Southern States. 

Cnemidoph'orus, a very little active brown lizard streaked with yellow 
and black, is found from Connecticut to Virginia and from Wisconsin to 
Mexico. In this family (Te'idce) there are over one hundred species dis- 
tributed throughout South and Central America and the warmer parts of 
North America. 

The "glass snake" (Fig. 201), our representative of the family An'guidoe, 
has a long brittle tail. Its brittleness is due to the fact that not only are 



246 



BRANCH CHORDATA 



the caudal vertebrae loosely joined together, but each vertebra is provided 
with a middle cartilaginous partition, so that it is easily separated. The 
caudal vertebrae of the Geckones and of most Lacertae break in the same 
manner. It is one means of self defense, as the animal escapes with only 
the loss of its tail. The popular notion of the pieces being collected again 
is without foundation. When " the tail is broken off," and this is always 
at this cartilaginous partition, " the cells of the remaining half reproduce a 




Fig. 202. — An'olis or American chameleon {Anolis principalis). Al- 
though the general color of the animal beneath is white, the upper parts 
may quickly assume hues varying from a vivid emerald green to a dark 
iridescent bronze color. (From Baskett and Ditmars, " The Story of the 
Amphibians and Reptiles," D. Appleton and Co., Publishers.) 



new tail." This new tail, says Gadow, is only a " sham tail," since it does 
not consist of a series of vertebrae, but of " a non-segmented rod or tube of 
fibrocartilage." 

This lizard cannot climb, and does not like the water, so it may be said 
to be entirely terrestrial. Its food consists of " snails, insects, worms, mice, 
small lizards, birds, and vipers." It shakes its prey until the victim is 
stunned, then chews and swallows it. It does not bite when caught, but 
winds about the wrist and emits a stinking discharge. It hides among the 



LACERTILIA 247 

leaves and in the sand under bushes. This species lays eggs, though some 
of its family are viviparous. It hides its eggs under moss and leaves and 
the young mature very slowly, taking several years to reach maturity. 

The American Chameleon and its Relatives. — Our very interesting lit- 
tle hzard (An'olis) (Fig. 202) of Florida and the Carolinas is commonly 
called a "chameleon," but the real chameleon is a native of Africa. The 
" green chameleon " (Anolis) has the power of suddenly and voluntarily 
changing its color to adapt itself to its environment. Experiments upon 
this animal m our laboratory proved that it changes color more rapidly 
when placed upon objects with natural colors than it does upon artificially 
colored ones. It is arboreal and insectivorous. The males have " large 
gular sacs which can be distended by the hyoid bones." These sacs are 
white, with occasional red lines and spots, but when mflated they become 
crimson. The Anolis is 5 or 6 inches long. 

Another member of this family is our little Swift, common in the forests 
and fence corners of the United States as far north as Michigan . It delights 
to lie basking in the sun, but disappears quickly when disturbed. 




Fig. 203. — The " homed toad" (Phrynoso'ma blainvillei) . The spiny cov- 
ering repels many enemies. (From Jordan and Kellogg, " Animal Life," 
D. Appleton and Co., Publishers.) 

Another member is the very interesting little hzard called the "horned 
toad"! (Fig. 203), Phrynoso'ma, found in the dry regions of the Southwest- 
ern States. The body is oval in form, rather flat and broad, with a short 
conical tail. It is covered with irregularly shaped keeled or spiny scales, the 
head being "bordered posteriorly with osseous spines." The small eyes are 
each protected by a ridge running backward above them. The ventral side 
of the author's pet "horned toad," a specimen from southeast Kansas, is 
yellowish in color, with a number of brown spots dotted over it. The scales 
are small and regular. The general color of the animal, dorsally, is grayish 
or yellowish brown, affording, together with its irregular and roughened sur- 
face, an excellent protective resemblance to the sand in the desert regions, 
in which it hkes to sink until the spines of the head alone stick out. Thus 
some species, at any rate, lie concealed through the night and on cloudy 
days. They are liveliest in the middle of the day and delight in the hot sun. 
When alarmed they shut their eyes and lie flat on the sand. Their food 
is insects, which they catch as toads do with their tongues, which are smooth, 
short, and scarcely at all notched, and can be thrust out a short distance 

1 Better, "Horned Lizard." It is not a toad (Amphibian, it is a reptile). 



248 BRANCH CHORDATA 

only, perhaps not over 2 inch. " Horned toads " will endure long fasts. 
They hibernate in winter. All species are viviparous and the young at 
one litter number seven or eight. 

Another Iguana (tuberculata) , of South and Central America and the 
West Indies, is sometimes 5 or 6 feet long and weighs nearly 30 pounds. 
It spends much of its time in trees, but when alarmed plunges into the 
water below it. It lays about two dozen eggs in a hole in the side of the 
bank. The flesh of these animals is much prized for food by the natives. 

The Monitors. — The one genus ( Var'anus) of this family ( Varan'idcB) 
consists of about thirty species. They are found in Africa, but not in 
Madagascar, in Australia, and in Southern Asia. They have long forked 
extensible tongues. They are large, attaining the length of 4 or 5, or even 
6 feet. Some are found in desert or dry regions, while others are semi- 
aquatic. The natives of some regions use the flesh of the monitors for 
food. The monitors are rapacious, devouring any animals which they 
can get. "The Monitor {Var'anus nilot'icus) is a great water-lizard that 
lives in the Nile. It is the principal enemy of the crocodile. When full 
grown it reaches a length of 6 feet or more." — Kellogg. 

Library Work. — See Gadow or other large works on reptiles 
for an extended description of Lacertilia of the tropical regions. 
The '' Flying Dragon " and other interesting forms are well 
worth your study. Baskett and Ditmar's '' Story of Amphib- 
ians and Reptiles " relates many interesting facts in a simple, 
yet instructive manner, also, Hornaday's " American Natural 
History." Do not fail to read the larger works. Get beyond 
mere text-book study of these wonderful forms in this and other 
lands. Broaden your own horizon. 

ORDER IV. CHELONIA 

Turtles vary in size from a few inches in length to 6 or more 
feet in some marine forms. The turtles of to-day are small as 
compared with some extinct forms. They vary in weight from 
a few ounces to over 1000 pounds. There are marine, fresh- 
water, and land forms, while the " gophers " of the South bur- 
row in the ground. 

Skeleton. — Turtles are easily recognized by their shell or 
exoskeleton. The dorsal portion of the shell is called the cara- 
pace, and the ventral portion the plastron. The covering of this 
shell consists of horny epidermal plates. These are thin, and 
when pulled off reveal the bony shields beneath. 

The hony carapace (Figs. 204, 205) is composed of the spines of 
the dorsal vertebrae, flattened, the ribs broadened out and joined 
to each other by sutures, also to the outer marginal row of 



CHELONIA 



249 




Fig. 204.— Bony carapace of turtle with epidermal plates removed to reveal 
bony shield with portion missing. Dorsal view. 




Fig. 205. — Bony carapace of turtle. Notice how the ribs are broadened and 
joined by sutures. Ventral view. 



250 BRANCH CHORDATA 

dermal bones, all fused into one bony carapace which is covered 
by epidermal plates. The plastron consists of epidermal plates 
underlaid with bony shields. The head, limbs, and tail may be 
more or less withdrawn under the carapace for protection; in 
some forms so completely that there is no part of the turtle 
visible outside of the shell. 

They have four short, strong, clawed, pentadactyle limbs, or, 
in the case of some marine forms, flippers. The marine paddle- 
limbed forms are usually designated as turtles, and those with 
walking limbs as tortoises. 

The bones of the head are firmly united. The jaws are 
toothless, but are inclosed in sharp horny beaks, with which 
they seize and crush their prey and then swallow it whole. 
The pectoral arch is a "triradiate structure, of which the 




Fig. 206. — Skeleton of snapping-turtle with portion of carapace sawed off 
to show interior. Cleaned and mounted by students ; (much reduced.) 

most ventral and posterior ray ending in a free extremity is 
the coracoid, while the other two are the procoracoid and the 
scapula with the suprascapula, which are fused at their glenoid 
ends."^ The pelvis is strong, consisting on each side of the 
pubis, the ischium, and the ilium. These meet at the articular 
surface of the hind limb. The vertebrae are few as compared 
with those of the snake. Those of the neck fit into one another 
with ball-and-socket-joint. There is no trace of a sternum or of 
sternal ribs. 

Digestive System. — The tongue is usually soft and wide and 
not extensible. The esophagus is covered with "conicaL pro- 
jections pointing toward the stomach." There is no cecum. 

Food. — Some species are carnivorous, some are herbivorous, 

1 Parker and Haswell, vol. ii, p. 329. 



CHELONIA 251 

while others are omnivorous. Predacious species probably 
lie in wait for their prey. 

The respiration is unique. The large spongy lungs reach to 
the pelvis. In breathing the neck and limbs act like pistons in 
being drawn in and out. The throat is alternately inflated and 
emptied by the hyoidean apparatus when the neck is stretched 
out, thus the air is swallowed or pumped into the lungs. Since 
the lungs are so roomy and the animals poikilothermal, most 
turtles can live for a long time without breathing, sometimes 
remaining under water for hours or even days. 

Special Senses. — Their eyes, though comparatively small, 
are their most highly developed sense organ. They are situ- 
ated far forward on the head and protected by two lids and a 
nictitating membrane. The nostrils are terminal; thus by ex- 
posing a minimum portion of the head above water they are 
able to breathe and see what is going on about them, compara- 
tively free from danger. The sense of smell is well developed, 
many species showing a choice of certain kinds of food which 
they distinguish by smell. The sense of hearing is not well 
developed. That they distinguish sounds is evident from 
their voice, which Gadow declares is very tiny and piping during 
the pairing season. Some species, at least, snap their jaws 
together when angry, and when the head and limbs are with- 
drawn they make a hissing sound. Holder says the male 
" elephant turtle " of the Galapagos Islands " utters a hoarse 
croak or bellow during the breeding season." They are fright- 
ened by noise. The tympanic membrane in most water forms 
is thin and quite exposed. In land tortoises it is often thick and 
covered with the skin. Turtles, contrary to the notion of small 
boys, are very sensitive to the touch, both upon the shell and 
upon the soft parts. 

Multiplication. — Turtles lay their eggs at night in the sand, 
cover them carefully, and leave them for the heat of the sun- 
warmed sand to hatch. 

The young are like the adult in general, but differ somewhat 
in color. 

Enemies and Defense. — They are preyed upon by carnivo- 
rous birds, fishes, alligators, and by men. They defend them- 
selves by closing up their shell, as the box turtle; by snapping 



252 BRANCH CHORDATA 

and scratching, as the snapping turtle; by swimming away or 
by hiding in the mud, and thus escaping by the protective 
resemblance. They hibernate in winter in this latitude. 

The leathery shelled sea-turtle {Sphar'gis coriacea) is the largest of all 
recent turtles. It is from 6 to 8 feet long, and of a dark brown color, and 
may weigh 500 pounds or more. It is widely distributed in the tropical 
seas, but it is abundant nowhere. The dorsal and ventral portions of the 
weak bony shell are continuous. It is buried under a layer of fat which 
yields " about a pint of oil to each square foot."^ The sea-turtles have 
long fiat triangular flippers without toes or claws. The front flippers are 
long. Its flesh is not edible. 

Hard-shelled Sea-turtles (Chelon'idoe) . — In this group is found the green 
turtle, one of the most widely distributed of the Atlantic turtles. It is 
found from Long Island to Cuba and south to Brazil and also in the 
Indian Ocean. Its flesh is prized for food. It varies in weight from 50 to 
500 pounds. 

The tortoise-shell turtle, from which is obtained the valuable tortoise 
shell, has its upper jaw terminated in a strongly hooked beak. Until the 
animal is very old the shields overlap one another from before backward. 
The scales are clear yellowish horn beautifully mottled with black and 
brown. These tin-tles do not reach the size of the green turtle; the largest 
one on record, says Gadow, is 34 inches long. They range over all the 
tropical and subtropical seas, being found occasionally around the Bahama 
Islands. 

The soft-shelled turtles {Trionych'idce) are of wide distribution both in 
time and space. The shell is very flat and almost circular. It is imper- 
fectly ossified both above and below, and terminates at the edges in thin 
plates of leathery skin. When properly cooked the shell is tasty. ^ These 
turtles are brown, mottled with black above and clear white below, and 
weigh from 20 to 30 pounds. 

The Snapping Terrapins (Chelyd'ridoe) . — This family includes the alli- 
gator snapper, the largest North American terrapin of the Gulf States, and 
our common " snapping turtle " found everywhere in fresh- water ponds 
and streams. The snapping terrapin has very powerful strongly hooked 
jaws, a long tail with a crest of bony compressed tubercles, and a small 
cross-shaped plastron. It seldom leaves the water. It is carnivorous, very 
voracious, and savage. It is destructive to fishes and water birds. 

The Smooth-shelled Terrapins (Emyd'idre). — The diamond-back terra- 
pin is found (or was until so much hunted for food) in salt marshes from 
New York to Teaxs. It varies in color from greenish to dark olive or black 
(rarely). It is small, one weighing a pound is considered large. It is 
regarded as the choicest variety for a terrapin stew. It is said that there 
are several " terrapin farms " in the South in which this turtle is being 
reared for the market. Unless some such provision is made they will soon 
be exterminated. 

The painted terrapin {Chry'semys pic'ta) is common in most regions east 
of the Mississippi. The shell is much depressed. The plates of the cara- 
pace in Chrysemys picta are greenish black edged with yellow, those about 

1 Hornaday, p. 331. 

2 Ibid. 



CROCODILIA 253 

the margin being conspicuously marked with red. The plastron is yellow, 
blotched with brown. There are markings of yellow and red upon the 
sides, neck, limbs, and tail, a pair of bright j'ellow patches behind the eyes, 
and a smaller pair on the back of the head. The toes are strong and broadly 
webbed. They are especially fond of insects and worms. They are very 
shy and active. Chrysemys marginata is a western form. 

The common box-turtle {Cistu'do), a terrestrial member of this group, is 
buUt for life on land. Its carapace is high and it can withdraw its head, 
legs, and tail within it. Across the center of the plastron is a double 
hinge, so that when disturbed it completely shuts itself in the box, and 
nothing short of injuring the shell can harm it. One was once subjected 
to a strong dose of chloroform in our tight-covered "' kiUing jar "for two 
hours with little or no effect, so tightly was it shut up in its box. It is surely 
a good illustration of special adaptation to environment. Since it cannot 
rim, like the rabbit, nor swim, like its relatives of the streams, it closes up 
its house and remains motionless. It is found from New York to Missouri 
and southward. 

The musk terrapin (Aromoch'elys odora'tics), a representative of the family 
Kinosternidce, is a small fresh-water specimen which has a strong, musky 
characteristic odor. Its food consists of aquatic insects, small fishes, and 
worms. 

The Land Tortoises (Test udin' idee). — The giant tortoise, which inhabits 
the Galapagos Islands and two islands of the Inchan Ocean, is the only sur- 
vivor of a race of giant tortoises of the Reptilian Age. A specimen once 
in the New York Zoological Garden weighed 310 pounds, and was estimated 
to be four hundred years old. 

Almost every island of the Galapagos group has had or has 
its own peculiar form of tortoise. How they got to these islands 
or where they came from it is impossible to say definitely. 
They could not have migrated, since land tortoises are easily 
droTsaied, and anj^way, " there are now none of their kind on the 
continents of Asia, Africa, or South America."^ So it is as- 
sumed that they are descendants of tortoises once populating 
the land which, except these islands, now lies below the Indian 
Ocean. 

Our native species of this family is the Gopher tortoise, found 
in the pine barrens of the Southern States. 

ORDER V. CROCODILIA 

Crocodiles and alligators are the largest of living reptiles, 
some of the largest crocodiles attaining a length of 30 feet. 
They are covered with horny plates or scales. 

The head is remarkable for its powerful jaws, whose enor- 
mous gape enables the animal to seize and crush its prey. 
The eyes, nostrils, and ears are on top of the head. While 

1 Gadow. 



254 BRANCH CHORDATA 

exposing only a small part of its body, it can see and hear well 
the approach of an enemy. " Crocodiles are the only reptiles 
whose nostrils open in the throat behind the palate instead of 
directly into the mouth cavity. This enables the crocodile to 
drown its victim without drowning itself, for by keeping its 
snout above water it can breathe with its mouth wide open."^ 
When under water the nostrils are closed by a valve. 

Limbs and Tail. — Their four limbs are stout, short, and 
powerful. The tail is strong and compressed. It aids the 
animal in locomotion, in self-defense, and in knocking its prey 
off the bank into the water, where it is seized and held under 
water until strangled to death. 

Habits. — They are aquatic and nocturnal in activity, feed- 
ing at night upon fishes, birds, mammals, and whatever they can 
capture. Hornaday describes how an alligator dismembered 
its victim. It seized the prey by one leg, whirled itself round and 
round till the leg was twisted off. He saw another shake a com- 
panion until the skin of its back was torn in two. 

They hibernate in temperate regions, and estivate or migrate 
in tropical regions when drought overtakes them. 

The Florida crocodile digs burrows in the sandy banks. The 
entrances are wholly or partly under water. At the farther end 
the burrow is wide enough for the crocodile to turn round in. 

They lay their large white eggs in the sand away from the 
water, or build rude nests or mounds in which they deposit their 
eggs in layers and watch and defend them until the young are 
hatched. Ditmars says, "The alligator has entire head broad, 
bluntly rounded at snout. The crocodile has head triangular; 
becoming very narrow toward snout." 

The ga'vial of India (Fig. 207) is long, and slender snouted. The animal 
may reach a length of 20 feet, but is harmless to man, being a fish-eater. 

Alligators. — The male alligator may reach a length of 12 feet and the 
female that of 8. The male has a heavier and more powerful head and is 
the more brilliantly colored during the breeding season. The large nest is 
built by the female on the bank of a stream or pool. The young are active 
and shift for themselves. The alUgator finds its northern limit in North 
CaroUna, about 35° North Latitude. From here south they abound near 
the mouths of creeks and rivers as far south as the Rio Grande. They 
ascend the Mississippi to 33° 50" North Latitude, or to the mouth of the 
Red River. 

There is a small species of alligator in China. It is about 6 feet long, of 
a greenish black color dotted with yellow. 

1 Dodge, p. 476. 



CROCODILIA 



255 






Fig. 207. — Gavial (Gavia'lis gauge' tica). (From Baskett and Ditmars, 
" The Story of the Amphibians and Reptiles," D. Appleton and Co., 
Pubhshers.) 




Fig. 208. — Crocodiles. (From Baskett and Ditmars, " The Story of the 
Amphibians and Reptiles," D. Appleton and Co., Publishers.) 



The caiman, of Central and South America and the West Indies, is some- 
thing hke our alligators and may reach a length of from 6 to 20 feet. 

The crocodile (Fig. 208) of the Nile and Madagascar and Asia is the 
largest of the order, sometimes reaching a length of over 20 feet. Hornaday 
says four species of crocodiles are found in America, and that only three of 
the nineteen species of crocodiles are dangerous to man, the most dangerous 



256 BRANCH CHORDATA 

of these being the " salt-water crocodile " of the Malay Peninsula. The 
American crocodile and the alligator are not dangerous to man. 

" The Florida crocodile is the only crocodile which inhabits a country 
that is visited by killing frosts."^ It is most abundant in low wet lands and 
shallow water, where the mainland sinks into the gulf. There is a Cuban 
crocodile and two South American species. 

Distribution of Reptiles. — The animals of this class are 
generally tropical and subtropical. Snakes are said to extend 
farther north in America than do lizards. In Europe snakes are 
not found north of 60°, while lizards are sometimes found farther 
north or at an elevation of ten thousand feet. 

Lizards are the most numerous of reptiles at the present time, 
and are found in all except the circumpolar regions. 

Chelonia are also widely distributed in the tropical and tem- 
perate regions. 

The alligators occur only in North America and in China, and 
the Caimans are found only in Central and South America. 
Crocodiles are distributed over Africa, southern Asia, northern 
Australia, and tropical America, there being one species in 
Florida. 

True reptiles are known to have existed in the Permian Pe- 
riod. Indeed, there was such a 'Variegated reptilian fauna" that 
it is believed their ancestors must have lived in the Carboniferous 
Period. One of the Permian orders (Theromor'pha) exhibits cer- 
tain strong points of resemblance to the earliest amphibians and 
other points of resemblance to the lower animals. They have 
been found in rocks of the Permian and Triassic Periods, but in 
none of the more recent formations. These fossils have been 
found in Texas, South America, Europe, Africa, and India. 

Lizard-like forms (Sauroptery' gia) existed in the Cretaceous 
and Triassic and possibly in the Permian periods. They varied 
from small forms up to those of 40 feet in length. A fish-like 
form (Ichthyoptery'gia), varying from 30 to 40 feet in length, ex- 
isted from the upper Triassic to the upper Cretaceous periods. 
In the Triassic were also forms allied to the crocodile. 

One of the most characteristic of the Mesozoic orders of 
reptiles was the Dinosauria, many of which existed in the Triassic 
Period. Some were herbivorous, others carnivorous. Some 

1 Hornaday. 



CROCODILIA 257 

walked on all fours, others occasionally or habitually walked 
upright, after the manner of birds, with which they had many 
structural features in common. Their size was so great that the 
footprints measured from 14 to 18 inches. The length was 
sometimes 60 to 70 feet and the height nearly 20 feet. 

The earliest turtles were found in the Triassic of Europe. 
True lizards appeared and turtles abounded in the Jurassic. 
The Pterosau'ria appeared in the Jurassic. They had toothed 
jaws and were winged like a bat. The spread of wings did not 
exceed 3 feet. In the Cretaceous Period the spread of wings was 
20 feet. Gigantic carnivorous marine lizards swarmed on the 
Atlantic and Gulf coasts and in the interior seas of that time. 

In the tertiary period reptihan life shows a great change, the 
animals being neither so large nor so varied. 

All the fossil snakes, except one found in the cretaceous, have 
been found in the tertiary period.^ 

It is plain to be seen why the Mesozoic Era is called the "age 
of reptiles," and how closely related the reptiles are to both 
amphibians and birds. They differ from amphibians in having 
bodies covered with scales, in having but one occipital condyle, 
in having the embryonic membranes, the amnion and allantois; 
in Crocodilia, in having a four-chambered heart ; in never having 
gills, and in never having a tadpole stage. They differ from birds 
in having scales, but never feathers, and in the circulation (being 
poikilothermal) . If we include the extinct forms, there will be 
found many points of similarity between reptiles and birds. 
Hence it is believed that amphibians, reptiles, and birds have a 
common ancestry. 

Economic Importance. — As has been mentioned, many rep- 
tiles are used for food. The skins of rattlesnakes and boas are 
made into bags, cases, boots, saddle cloth, etc. The oil of the 
rattlesnake and boas is valuable, and that of the copperhead is 
used in medicine. The scales of the tortoise-shell turtle are 
valued for combs and ornaments, and the oil from its eggs is 
used in dressing leather. From alligators we get valuable 
leather, oil, and musk. The teeth, flesh, hide, and oil of croco- 
diles are valued. 

Most of our common forms are not dangerous to man, and, 
^ Parker and Haswell. 
17 



258 BRANCH CHORDATA 

any way, will not attack him if unmolested. A few forms of 
snakes and crocodiles are dangerous to man. 

Important Biologic Facts. — The embryonic membranes, the 
amnion and the allantois, first appear in this class. Respiration 
is by lungs. True nostrils appear. The heart is four cham- 
bered in Crocodilia. 

Classification. — 

Order. Examples. 

I. Rhynchocepha'lia. Sphenodon punctatum. 

II. Ophid'ia. Snakes. 

III. Lacertil'ia. Lizards. 

IV. Chelo'nia. Turtles. 

V. Crocodil'ia. Crocodiles, alligators. 

CLASS V. AVES 

" I have considered the birds, 
And I find their life good. 
And better, the better understood." 

(McDonald.) 

In existing forms, birds are feathered chor dates having no 
teeth, but from paleontology we learn that some of the fossil 
birds (Figs. 209-212), as the Archceop'teryx (Fig. 212), of the 
Jurassic Period, had teeth and a long vertebrated tail. 

Birds have several characteristics in common with reptiles, 
among which are the large eggs, the lack of a complete dia- 
phragm, the quadrate bone connecting the lower jaw with the 
skull, and the single occipital condyle. It is believed that in the 
early stages of their development birds floated in the air by 
means of a patagium, or wing membrane, and that even "feath- 
ers were used at first as a means of sailing down" after having 
crawled up to some height by the use of claws on the "fingers," 
vestiges of which are yet shown by many birds, such as the 
turkey, the vulture, certain ostriches, swans, thrushes, and 
young gallinules, which have claws variously located on the 
wing tips. 

Covering. — The lower part of the legs is covered with hard, 
reptile-like scales, or epidermal shields, for protection. The 
beak and claws are also horny epidermal structures. 



AVES 



259 



The skin of a bird is thin and the body is not uniformly 
covered with feathers (Fig. 213). There are many bare spots, 
as may be readily seen by turning back the feathers on the neck 
or breast. The bare spaces, apteria, are concealed by the over- 
lapping feathers. Note where the feathers grow. These spaces 
are called pterylce, from two Greek words meaning "feather 
forest." 

Feathers are homologous with scales, as "the feather may be 
regarded as a cornified outgrowth from the skin, which has arisen 




Fig. 209.-1 chthy or' nis victor, X i. Fig.210.— Hesperor'nisregal'is,XA 
(Restored by Marsh.) (Restored by Marsh.) 

on a papilla of the derma. "^ A large wing feather, for example, 
is made up of the central stalk and the expanded part, or vane. 
The hollow portion of the stalk nearest the body is the quill, 
and the remaining part, the rachis or shaft. The vane is com- 
posed of side branches or barbs, the barbs of side branchlets or 
barbules, which are provided with hooks. The hooks of one 
barbule interlock with those of the next and thus hold the parts 
of the vane together. In down feathers the hooks are lacking. 

^ Hertwig. 



260 



BRANCH CHORDATA 



The large feathers on the wing and tail are called quills; the 
similar but smaller ones on the body, the contour or outline 
feathers; those without barbs, down; and the hair-like ones, the 
filoplumes or pin-feathers. These different kinds have various 




Fig. 211. — Dinor'nis giganteus, Xg'g. (From a photograph of a skeleton in 
Christchurch Museum, New Zealand.) 



uses. Can the student see the advantage to the bird of each 
kind of feather? What use does man make of the different kinds 
of feathers? 

"Since the feathers are not only for protection, but give to 
most birds the power of prolonged flight, they predict a special 



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261 



mode of life. The character of the skeleton, the respiratory 
organs, and, in part, the sense organs and brain are connected 
with the powers of flight. "^ 

Variation in Plumage.— The changing of the feathers and the 
colors of birds is very little understood. The nestling plumage 
may be so meager that we speak of the young as naked, but the 
precocial forms, as the grouse, snipes, and ducks, have a thick 
covering of down. This is followed by what is known as the 




B 



Fig. 212.—^, Archoeoptenjx macrura, restored (Fowler). B, Section of the 
tail (after Owen). (Romanes). 

first piumage, which appears more quickly upon the naked than 
upon the down-covered young and which may be unlike that 
of either parent. In most land birds this is soon followed by 
the immature plumage to be worn during the winter. This 
plumage may be like that of the adult parent of the same sex, 
or it may be that both immature males and females may resemble 
the adult female, or they may be unlike either parent. In the 

^ Hertwig, p. 604. 



262 



BRANCH CHORDATA 



first, second, or even the third spring the plumage becomes like 
that of the adult. 

The time of molting varies not only among different species, 
but often among different individuals of the same species, ac- 
cording to sex, age, and physical conditions. All birds molt after 
the nesting season. Some birds lose a few of the body feathers 
in the next spring before the nesting season, while many lose the 
body feathers, but not those of the wing and tail. Some change 




Fig. 213. — Pterylae and apteria of Gallus bankiva (Nitzsch): a, Ventral 
side; b, dorsal side. 



color by wearing off the fringes of the feather tips, and others 
at this season are adorned with special nuptial plumes,^ such as 
the aigrette of the heron, for which these birds have been so 
slaughtered. 

There are no periodic molts of the skin, as in reptiles, but the 
horny layer of the integument undergoes a constant renewal, as 
in mammals. Some penguins, it is said, "exhibit the old rep- 

1 Chapman, " Bird Life," p. 38. 



AVES 263 

tilian habit of shedding theirs in great flakes, with feathers 
attached."^ 

General Structure. — The skull (Fig. 214) is thin; the bill or 
horny beak varies much according to its use; and there is, as in 
reptiles, only one occipital condyle. The neck is long and flex- 
ible. In different kinds of birds, the number of neck vertebrae 
varies from eight to twenty-four. 

The wings are adapted for flight in our birds. While the 
ostrich cannot fly, its rudimentary wings are compensated for 
by its very strong legs, which are adapted for rapid running. 
No other animal has wings of the same structure as a bird's. 
The characteristic structure of the wing-bones is the hand. It 
is comparable with the human hand. 




Fig. 214. — Skull of parrot: 22, Premaxillary bone ensheathed in horn; 
15, nasal bones; v, mandible, the end sheathed with horn; I, malosquamosal 
zygomatic style or maxillojugal bar; g, postfrontal bone; o, lacrimal 
bone; n, nostril, showing also the articulation of the nasopremaxillary 
bone; e, quadrate bone; m, orbit; 1, occipital bone. (After Owen.) 

The legs and feet (Fig. 215) of birds are adapted -for running, 
scratching, swimming, or perching. Note the position of the 
thigh (femur) on the side of a bird. Do you see any advantage 
of such a position? Distally the femur or thigh is joined to the 
tibiotarsus and the fibula, which is found partially united with the 
tibiotarsus. The proximal row of tarsal bones unites with the 
distal end of the tibia, hence the name tibiotarsus or "drum- 
stick" in the chicken. The distal row of tarsal bones unites with 
the metatarsal bones to form the tarsometatarsus or simply the 
tarsus, which bears the usually four-clawed toes. One toe is 
generally directed backward and three forward. 

Where is the knee in the bird? The ankle? Do you see any 

1 Baskett, " Story of the Birds," p.. 33. 



264 



BRANCH CHORDATA 



advantage in this arrangement? Why do they differ from the 
structure and arrangement in the leg of man? 

The body skeleton (Fig. 216) is strong, hght, and flexible, as it 
must be for flight. Note how firmly the vertebrae are joined in 




Fig. 215. — The most important forms of birds' feet {b, c, d, f, n, from the 
regne animal) : a, Pes adhamans of Cypselus apus; b, P. scansorius of Picus 
capensis; c, P. ambulatorius of Phasianus colchicus; d, P. fissus of Turdus 
torquatus; e, P. gressorius of Alcedo ispida; f, P. insidens of Falco biarmicus; 
g, P. colligatus of Mycteria senegalensis ; h, P. cursorius of Struthio camelus; 
i, P. palmatus of Mergus merganser ; k, P. semipalmatus of Recurvirostra 
avocetta; I, P. fissipalmatus of Podiceps cristatus; m, P. lobatus of Fulica 
atra; n, P. steganus of Phaeton cethereus. (After Claus.) 



the back. Note also the very short bony tail, consisting of a 
few vertebrae fused into the pygostyle, which supports the tail 
feathers. The oil gland is situated near the pygostyle and from 
it birds get the oil for their feathers. Note also that the sternum 



AVES 



265 



is keeled in our birds, while the keel is lacking in the ostrich. 
The keel or carina is a basis of classification. Birds with the 
keel poorly or not at all developed are called Rati'tce, or raft-like 
birds, while the keeled birds are called Carina'tce, which group 
contains our native American birds. 

The shoulder-girdle is a peculiar device of flying creatures. 
It consists of the scapula, coracoid process, and the V-shaped 




Fig. 216. — Skeleton of a sparrow: q, Quadrate bone, peculiar to reptiles 
and birds and some amphibia; b, breast-bone; m, merry-thought or collar- 
bone; c, coracoid bone, over which the tendon works to pull up the wing; 
p, plowshare-bone, on which the tail grows. Wing-bones: a. Upper-arm; 
e, elbow; fa, fore-arm; w, wrist; t, thumb; ha, hand. Leg-bones: th, Thigh- 
bone; k, knee; I, lower part of leg; h, heel; /, foot. (From Holder, Amer- 
ican Book Co., Publishers.) 

clavicle, or "wish-bone." The pelvic girdle consists of three 
paired bones, ilium, ischium, and os pubis, which unite at the 
cup or acetabulum, which holds the head of the femur. 

A careful study of the skeleton of a bird shows its marvelous 
adaptation to its uses. It must be strong to support the great 
muscles of flight and to protect the viscera, while it must be light 
and flexible for the purpose of aerial locomotion. 



266 



BRANCH CHORDATA 



The Digestive System. — The mouth is devoid of teeth in exist- 
ing birds. Extinct birds (see Figs. 209 and 210) had teeth (see 
Geology) . Can the student see any reason why birds have lost 
their teeth? The beak (Fig. 217) is very strong in birds of 
prey, such as the eagle and hawk. The mouth opens into the 




Fig. 217. — Forms of beaks (a, b, c, d, k, after Naumann; g, i, m, o, regne 
animal; I, from Brehm) : a, Phoenicopterus antiquorum; b, Platalea leucorodia; 
c, Emberiza citrinella; d, Turdus cyanus; e, Falco candicans; f, Mergus 
merganser; g, Pelecanus perspicillatus ; h, Recurvirostra avocetta; i, Rhyn- 
chops nigra; k, Columba livia; I, Balceniceps rex; m, Anastomos coromande- 
lianus; n, Pteroglossus discolor; o, Mycteria senegalensis ; p, Falcinellies 
igneus; q, Cypselus apus. (After Claus.) 



esophagus, which opens into the large crop, in which the bird rap- 
idly stores its food, which is passed on to the glandular stomach 
or proventriculus. It is then passed to the muscular gizzard, 
where with the aid of gravel and other hard substances, the food 
is ground fine. The spleen is a small, red ovoid body at the right 



AVES 267 

of the proventriculus. Following the gizzard is the duodenum. 
The pancreas is in a loop of the duodenum and pours its secre- 
tion into it. The large liver pours its bile into the duodenum. 
The ileum continues from the duodenum to the large, straight 
intestine, the rectum. The junction is marked by long, blind 
pouches or ceca. The large intestine ends in an enlargement 
called the cloaca, or sewer, because it receives the undigested 
food, the excretions of various organs, and the eggs, all of which 
pass out by one external opening. 

Circulatory System. — Circulation is complete. The heart is 
large and composed of two auricles and two ventricles. The 
right aortic arch persists in birds, while the left persists in man. 
The circulation is double, pulmonary and systemic. The sep- 
tum is complete between the ventricles, thus keeping the impure 
blood (venous) from the pure blood (arterial). 

The Respiratory System. — The pharynx opens by the glottis 
into the trachea, which divides and sends ramifying branches into 
the lungs. The lungs connect with the system of air-sacs which 
aid the bird in flight. "Usually five pairs of these sacs are pres- 
ent, largely in the coelom, but extending in between the muscles 
(breast and axillary region) and also into the bones."^ The 
syrinx or voice-box is at the junction of the bronchial tubes 
and the trachea, where they enlarge to form it. This syrinx 
is especially well-developed in singing birds. 

Many of the bones are hollow and filled with air. Thus is 
the inspired air distributed over the body, so that the aeration of 
the blood is not confined to the limited area of an orcUnary organ 
of respiration. The bird is a very warm-blooded animal, and to 
keep up its heat it must use oxygen rapidly. This it does by its 
rapid breathing, which may be at the rate of sixty per minute. 
The temperature of birds is from 100° to 110° F., while in man 
the temperature is 98.6° F. The temperature is also kept up by 
the non-conducting feathers and by the absence of skin glands, 
with the exception of the oil gland at the base of the tail. 

In the absence of a diaphragm, expiration is effected by the 
drawing of the sternum toward the spinal column and the bend- 
ing of the hinged ribs. Inspiration is effected by the straighten- 
ing of the ribs brought about by relaxing the muscles. Thus the 

1 Hertwig. 



268 



BRANCH CHORDATA 



lungs, which are attached to the ribs, are alternately enlarged 
and contracted. 

The Excretory System. — With each expiration the lungs 
excrete carbon dioxid and other waste products. The kidneys 
are dark-colored, paired organs lying in the pelvic region close 
against the back. They open into the cloaca by the ureters. 

The Reproductive System. — Anterior to the kidneys are the 
reproductive organs, which open into the cloaca. Multiplica- 
tion is by eggs, which are noted for their very large size. The 
egg begins in the left ovary, the right ovary not being developed. 




Fig. 218. — Diagrammatic longitudinal section through an undeveloped 
hen's egg: Bl, Germinal disk; GD, yellow yolk; WD, white yolk; DM, 
vitelline membrane; EW, albumen; Ch, chalazae; S, shell membrane; KS, 
calcareous shell; LR, air-chamber. (After Allen Thompson.) 



It passes into the oviduct, where it is fertilized. As it passes on 
down this duct it acquires the yolk, the white, the hnings, and 
the shell from glands that secrete these essential parts of the egg 
(Fig. 218). The birds are developed by the large amount of 
food within the shell. 

Incubation, or sitting upon the eggs for a definite period of 
time, is peculiar to birds, though the python is said to coil upon 
its eggs. The number of eggs in a clutch varies from one to a 
score or more. Some birds, like the pigeon, are monogamous, 
choosing one mate for life, but many are polygamous, like the 
barnyard fowls. It is said that most pretty birds are flirts. 



AVES 



269 



The young of some birds are altricial (Fig. 219) and must be 
cared for and fed by the parent or parents; while others, hke 




Fig. 219. — The altricial nestlings of the blue jay {Cyanocit'ta crista'ta). 
(From Jordan and Kellogg, " Animal Life," D. Appleton and Co., Publish- 
ers.) 



the quail, are precocial and are able to feed and care for them- 
selves as soon as hatched. 

The nests of birds vary much according to the habitat of the 
bird and the material available (Fig. 220). Birds, like men, use 
the material they find about them. Ground birds use the ma- 



270 



BRANCH CHORDATA 



terial they find on the ground, while the arboreal forms more 
often use small twigs for their nests, which they sometimes line 
with finer material, such as strings and hairs. The woodpecker 
uses no material but the tiny chips he has made in digging the 
hole. The swift glues together the twigs of its nest by a sticky 
saliva. According to the manner in which they construct their 
nests, birds have been variously styled weavers, tailors (Fig. 
221), carpenters, or masons, and their tools vary according to 




Fig. 220. — Brown pelican and nest in young cabbage palmetto. (Photo- 
graph by Frank M. Chapman.) (Y. B. U. S. Dept. of Agricul.) 



the work to be done, or vice versa. Sometimes both sexes build 
the nest, or one collects the material and the other arranges it. 
In other cases the male sits by and sings, leaving the building 
to his mate. The position of the nest varies. It may be placed 
upon the ground, like that of the quail, or on a rock, like the 
penguin's, or suspended far out on the swaying branches, like 
the dehcate hanging nest of the oriole (Fig. 222). The object 
of the position, of course, is for protection. One must observe 



AVES 



271 



how well birds are protected by their colors, especially the fe- 
male birds at nesting time. 

The Nervous System and Special Senses. — The hrain (Fig. 
223) of birds is larger and more highly developed than that of 
reptiles. The cerebrum and cerebellum are larger. The cere- 
brum is smooth, but the cerebellum is convoluted transversely. 



Fig. 




221. — Tailor-bird (Orthot'omus suto'rius) and nfest. (From Jordan 
and Kellogg, "Animal Life," D. Appleton & Co., publishers.) 



The eyes of the bird are large, to meet the demands of far vision 
in flight. There are two movable eyelids and a third membrane 
called the nictitating membrane, which the bird can draw over 
the eye by a peculiar muscular arrangement. This membrane 
protects the eye from too bright Hght (Fig. 196). The yecten, 
"a comb-shaped growth of the coroid into the vitreous body," 
is a pecuhar avian characteristic. The avian eye is character- 
ized net only by the sharpness of vision consequent upon the 



272 



BRANCH CHORDATA 




Fig. 222. — Baltimore orioles and nest; the male in upper left-hand corner 
of figure. (From Jordan and Kellogg, " Animal Life," D. Appleton & Co., 
publishers.) 

large size and complicated structure of the retina, but also by the 
highly developed power of accommodation, and by the great mo- 
bility of the muscular iris in the dilation and contraction of the 
pupil. 

The ear is well developed. There is no external ear, but the 
opening to the tympanum is concealed by feathers posterior to 
the eye. The ear has three semicircular canals, the dilated 
cochlea, and a Eustachian tube extending to the mouth from 
each ear. 

Of the other senses it may be stated that touch is common in 



AVES 



273 



all parts of the body; that taste is poorly developed; that smelLis 
apparently not very acute, except in vultures or turkey buzzards 
and other carrion-eating birds. 




A B 

Fig. 223. — Brain of the hen (A, from above; B, from below): a, Ol- 
factory bulbs; 6, cerebral hemispheres; c, optic lobes; d, cerebellum; (i', its 
lateral parts; e, medulla. (After Carus, from Gegenbaur.) 

Behavior and Intelligence. — As has been said of other ani- 
mals, it is exceedingly difficult to judge what goes on in the mind 
of a bird without ever having been a bird. It is very probable 
that many writers upon animal intelligence give birds credit for 




Fig. 224. — Eye of a nocturnal bird of prey: Co, Cornea; L, lens; Rt^ 
retina; P, pecten; N.o., optic nerve; -Sc, ossifications of the sclerotic; CM, 
ciliary muscle. (After Wiedersheim.) 



a higher intelligence than they possess because they draw mis- 
taken conclusions from bird activities, or, more often, because 
observations have been inaccurate or incomplete. When a 

18 



274 BRANCH CHORDATA 

child perforins a certain action, we ascribe to him certain sensa- 
tions, emotions, or phases of intelligence. When a bird does 
the same thing, it is only fair to believe that these same activities 
are accompanied by similar, though perhaps less distinguishable, 
psychologic processes. If we deal fairly, and our observations 
are complete, much may be learned to add to the meager informa- 
tion given in our scientific books upon this fascinating subject. 
Always ask these questions: Exactly what did the bird do? 
Under precisely what circumstances? Possible causes? Most 
probable cause? Does the result of the bird's action prove that 
your conclusion is correct? 

Scientists differ widely in their opinions on bird mind, but it 
is thought that there is abundant proof that, in intelligence, 
birds stand next to mammals, if they do not surpass some of them. 
All will surely agree that birds feel pleasure and pain; that they 
exhibit surprise, fear, sexual feeling, sexual selection, parental 
affection, curiosity, industry, pugnacity, anger, jealousy, play, 
grief, and a wonderful homing instinct.^ Many examples are 
recorded which seem to show sympathy, revenge, recognition of 
persons, and affection for, or, at least, attachment to, their human 
friends. Birds recognize their offspring, they have memory, as- 
sociation of ideas, and communication of ideas. Examples are 
given by some of recognition of pictures. It is hoped that this 
will be further experimented with. Bower birds (Fig. 225) and 
others show an appreciation of beautiful surroundings, while 
many birds seem to appreciate the brilliant colors and songs of 
their mates. By experimenting with different colored foods 
it has been proved that birds can distinguish colors in objects 
and that they learn by experience and make intelligent choice. 
The best possible treatise on the psychology of birds is the living, 
acting bird which every student can have almost every day in 
the year. Study the birds. Make accurate observations and 
record them. Weigh your conclusions. 

The Migration of Birds. — There is no theory which satisfac- 
torily accounts for the periodic coming and going of the birds. 
One theory attributes it to the varying temperature. Another 
theory attributes it to a lack of food, but many of our birds come 
in March, when food is still scarce and the temperature low, and 

^ Romanes, " Animal Intelligence." Also Darwin, " Origin of Species." 



AVES 



275 



leave in August or September, when there is still an abundance of 
food. Another theory is that of securing better and more pro- 
tected breeding grounds. Nest concealing is possibly a factor. 
Chapman believes that the origin of this great pilgrimage " is 
found in the existence of an annual nesting season," and that it is 
exactly paralleled by the annual migration of certain fishes to their 
spawning grounds, and the regular return of seals to their breed- 
ing-rookeries. But what seems to us most strange is that the 




Fig. 225. — Bower bird {Chlamydera maculata) with bower. (From Brehm.) 

same species of birds takes the same definite route of migration 
for generations, except that its range is gradually lessened or 
extended. Chapman gives as an illustration of the stability of 
routes of migration the bobolinks, which are Eastern birds, now 
spread westward to Utah, yet, instead of migrating directly south 
through Texas and Mexico, they, "true to their inherited habit, 
retrace their steps and leave the United States by the round- 
a-bout way of Florida, crossing thence to Cuba, Jamaica, and 
Yucatan, and wintering south of the Amazon."^ The extent 
1 Chapman's " Bird Life," p. 60. 



276 BRANCH CHORDATA 

of these migrations varies. Some birds do not migrate, but 
stay all winter in the same locality, often changing from an 
insectivorous to a seed-eating life. Others migrate but short 
distances. The snipeis and plovers make extended migrations, 
going from the arctic regions to the tropics, some species travel- 
ling from Alaska to Patagonia. 

Parasitism. — The American cow-bird and European cuckoo 
lay thieir eggs in the nests of other birds, where the young are 
cared for by the foster parents, often at the loss of their own off- 
spring. 

Rivalry among birds may be by means of ornament, color, 
antics, battle, or song. The male is usually more brightly col- 
ored than the female and puts on his most brilliant attire at the 
courting season. Rarely the female is more brilliantly colored 
than the male (see p. 291). In this case she does the courting, 
but as a rule the female is much more inconspicuously colored, 
since she is generally the one which sits upon the nest, and it is 
to the interest of the family that she be protectively colored. 
Darwin believes^ in the choice of the female in mating, and that 
the attractiveness of the male may lie in the tinted or lengthened 
beak, or the striped or brightly colored feet, or the bright wattles 
or other appendages about the head; but the most common and 
the most brilliant display of colors is in the plumage. Some 
think that the health and vigor generally may be the cause of 
this brilliancy, but Darwin believes that it has been intensified 
from generation to generation by the choice of the females, thus 
perpetuating these characteristic pleasing colors and color-pat- 
terns in the offspring. Mr.'* Wallace, strangely enough, denies 
the female any part in the matter of mating, while he "ascribes 
to natural selection any secondary sexual character which is of 
practical use to the male in conflict with a rival. "^ Some birds 
seem to be more easily pleased by antics and pranks which are 
sometimes connected with the display of ornament and some- 
times not, as if he who made the biggest clown of himself was the 
favored suitor.^ A familiar example of the display of beauty- 
spots is afforded by the flicker which sits upon a twig facing his 

1 See Darwin's " Selection in Relation to Sex," " Descent of Man." 

2 Wallace's " Darwinism." 

3 Baskett, " Story of the Birds." 



AVES 



277 



sweetheart, "lifts his wings, spreads his tail, and begins to nod 
right and left as he exhibits his moustache to his charmer and 
sets his jet locket first on one side of the twig and then on the 
other, and she plays back at him in a similar peek-a-boo fashion." 
The drmnmingof the grouse and the bill tattoo of the woodpecker 
are efforts to charm. Odor has no part to play in the art of 
pleasing among birds, for the musk duck is said to be the only 
bird which secretes an especially odorous substance. 

Battle among birds may be for self-defense or for defense of 
young, but it is most commonly for rivalry, as both Wallace and 
Darwin believe. For bird battles there are various kinds of 
weapons. The cassowary has the elongated inner toe armed 
with a long straight claw and the short wing quills modified into 
spines. During the nesting season many males have wing spurs 
which subside into something like knobs when the season for their 
use is over. Unlike the bony wing-spur, the leg-spur is devel- 
oped from the skin. Some birds fight fiercely, while others merely 
run a bluff by some terrifying attitude, wherein they display 
their wing-spurs. 

Song. — There is much reason to think that the song of the 
male bird is a means of pleasing or courting the favor of his 
wished-for mate, though he afterward sings to cheer her during 
the period of incubation. The song often ceases when the 
young are hatched; there is something else to be done then. 
But the song is heard again during the preparation for the 
second brood. 

There are many call-notes for other purposes than rivalry. 
Chapman says that "call-notes form the language of every day 
life, while song is the outburst of special emotion." The call 
of the mother to her young in warning, in fear, in reassurance 
when danger is over, the cry of hunger or distress in the young, 
the thankful little chirp when feeding or when cuddling under the 
mother's wing, the scolding of both parent birds when an enemy 
approaches the nest ; all these and others have their significance 
in bird language. One would find this study far more interesting 
than that of a dead language and the opportunity for its 
pursuance is present everywhere. Try to imitate the vari- 
ous call-notes of the birds with which you are familiar and make 
a list. 



278 



BRANCH CHORDATA 



Classification. — The classification of birds seems to be chaotic, 
no two zoologists agreeing. Some claim birds are of too recent 
origin geologically to have differentiated as yet into well- 
marked ord??rs. They might be grouped as land birds and water 
birds, or as runners and flyers, but such classification would not 
be scientific. If there were a geologic series showing the nat- 
ural affinities, a natural classification would be a comparatively 
easy task, as all classification should be based on development 
and structure. 

Division A. Rati't^ 

Living birds are divided into two groups, the Rati'tce and the 
Carina'tce. Ratitse are birds with a raft-like or keelless breast 
bone, wings rudimentary or too small for flight, legs large, 
strong, and fitted for rapid running. As examples may be 




Fig. 226. — Ap'teryx austral'is, a nocturnal flightless bird with nostrils near 
the end of the bill. The external wing is shown in the upper part of the cut. 
(Romanes.) 

named the ostrich, emu, rhea, cassowary, kiwi (Fig. 226), and 
the extinct moa and other ostrich-like birds. None of these 
birds is native to the United States, but in recent years they 
have been imported into some parts of the west, as Pasadena, 
California, Salt River Valley, Arizona, and some other dry, warm 



RATIT^ 



279 



localities, where they are breeding and becoming of much value 
for their plumes. 

The ostrich is the largest of living birds (Fig. 227). It may 
attain to a height of 6 or 8 feet, and may easily reach, with 
outstretched neck, a height of 10 feet. It weighs from 375 to 
450 pounds. It is a rapid runner, a single stride is said to 




Fig. 227. — Ostrich twenty-six months old. (^Yea,r-ijooiv b. .s. Dept. Agri- 

cul., 1905.) 



cover 25 feet or more.^ It uses its two-toed feet in defense and 
its kick is dangerous. "The cry is said to be hoarse and mourn- 
ful, resembling the roar of a lion or the lowing of an ox." The 
eggs are 5 or 6 inches in length, and one ostrich egg equals a 
score of common hen eggs. They are laid in a hollow nest in 
1 Evans, "Birds," p. 28. 



280 



BRANCH CHORDATA 



the soil or sand and one nest may contain as many as twenty- 
five or thirty eggs, several hens laying in one nest. The male 
does most of the incubating, the eggs hatching in from forty to 
forty-five days. The ostrich is a native of Africa. It is found 
from Barbary to Arabia and even into Mesopotamia, where it 
has long been domesticated. ''The plumes are plucked or, 
preferably, cut twice a year." The flesh is coarse and little 




Fig. 228.— Ostriciu's inc days old. (Year-book U. S. Dept. Agricul., 1905.) 



used. The yearly sales in South Africa amount to nearly five 
million dollars. 

The three-toed rhea, or so-called ostrich, is a South American 
bird. Rheas are shorter than the ostrich and the feathers are 
rounded and very soft. Their favorite haunts are the "treeless 
flats of the Argentine Pampas, the scrub-covered plains of Pata- 
gonia, or the dry open sertoes of Brazil. "^ 

The cassowaries and emus have rudimentary wings, and they 
lack the ornamental wing and tail plumes. The hair-like coat 
is characteristic. The female cassowary is larger than the male, 
and both sexes are black. The plumage is made into rugs, mats, 
and head ornaments. 

1 Evans, "Birds." 



WATER BIRDS 



281 



Division B, Carinat^ 

This group contains the birds with a keeled breast-bone. It 
is usually divided into seventeen orders by American ornitholo- 
gists. The orders of birds are not well differentiated as compared 
with the reptilian orders. The classification followed for Car- 
inatae is that of Reed and Chapman in their "Color Key to North 
American Birds." 

WATER BIRDS 

Order I. Pygop'odes. — Auks, grebes, and loons are examples of 
this order of marine birds. Their legs are situated far back on 
the body, the feet are broadly webbed, and the bills are narrow. 
They are good swimmers and divers, and some are good flyers. 




Fig. 229. — Great penguin (Aptenody'tes patagon'ica.) (After Tenney.) 

The penguins, of which there are about twenty-eight species, are found 
in the Antarctic region and on the South American coast (Fig. 229). 
When on land these birds rest on the whole metatarsus and assume an erect 
attitude, their legs being situated very far back. They are famous swim- 
mers and divers, but they cannot fly. Their wings are degenerate, being 
really feathered flippers. These feathers in some species look more like 



282 



BRANCH CHORDATA 



scales. 1 When under water the wings act as paddles and the feet as rud- 
ders. Penguins are gregarious, swimming in schools, and are seldom 
seen on land except at the breeding season, when they go in great numbers 
to their rookeries. The nests of grass and leaves may be under stones or 
in caves or burrows. The male assists in incubating the two white or 
greenish eggs, which require six weeks to hatch. The young are blind and 
altricial, and are fed by the parents, which insert their bills in those of the 
young. The food of the penguin consists of crustaceans, mollusks, and 
fishes with a small amount of vegetable matter. The voice may be a 
hoarse bark, " croak or scream, or a murmuring sound, or, in the young, it 
may be a whistle." 

Order II. Longipen'nes. — These are mostly sea birds, with long 
wings and webbed feet. Gulls and terns may be named as ex- 




■" Fig. 230. — Franklin gull; 15 inches. (Photographed from specimen.) 

amples of this order (Fig. 230) . Gulls feed chiefly on fish, but 
one may observe hundreds of them about an ocean liner as it 
comes into port. They seek what is thrown overboard. They 

1 Hornaday. 



WATER BIRDS 



283 



are the scavengers of the water, feeding from the surface, 
are at home in the open seas. 



Gulls 



Terns are littoral (Fig. 231). They are more slender and active than the 
gulls, and have long forked tails and pointed bills. They nest in colonies, 
coming from the South in May and remaining until September. When 
in search of food the terns fly with the bill downward, while gulls carry the 
bill in a line with the body. Terns nest in colonies on islands. The nest 



/T, 





Fig. 231. — Terns in Southwest Harbor Key in Breton Island Reservation. 
(Year-book U. S. Dept. Agricul., 1905. Photo by Frank M. Miller.) 

is made of a few wisps of grass. The eggs, two or three in number, are 
laid in a depression in the sand or pebbles. The young of both gulls and 
terns are precocial. When frightened, both gulls and terns squat low 
near the ground and remain motionless until actually touched. 



Order III. Tubina'res are so called because the nostrils are 
carried well forward through the two round tubes that lie either 
along the top or the sides of the bill. The opening of the nostril 



284 



BRANCH CHORDATA 



is about half-way between the base and the tip of the bill. The 
bill is hooked like that of a bird of prey. "All are deep-water 
birds, strong of wing, and brave spirited beyond all other birds. 
The range of the order is worldwide. The most of them are 
found in the southern oceans." 



To this order belong the -petrels, " Mother Carey's chickens," which one 
sees hundreds of miles out on the ocean. The stormy petrels are the smal- 
lest of web-footed birds, being no larger than catbirds. Their note is shrill, 
and their flight butterfly-like. 

The wandering albatross, with an expanse of wing from 10 to 14 feet, 
is also a member of this order. It is a wonderful flyer, sailing for hours with- 
out resting, always with rigid, motionless wings, rising, descending, or turn- 
ing without a visible movement of them. It has been made immortal by 
Coleridge's " Rime of the Ancient Mariner." 







Fig. 232. — A little corner of Pelican Island. (Year-book U. S. Dept. 

AgricuL, 1905.) 



Order IV. Steganop'odes. — The members of this order have 
the four toes connected by a web. The bill has no lamellce. 
The nostrils are small or wanting and the throat is usually 
pouched. Here belong such large aquatic birds as the frigate 
or man-of-war bird, the cormorant, and the pelican. 



WATER BIRDS 285 

The frigate or man-of-war bird is a very long-winged, long-tailed bird 
of the ocean. Its legs are very weak, but it is a remarkable flyer. It is 
found hundreds of miles from shore on the ocean. These birds live in the 
southern waters of both hemispheres. In the Cocos-Keeling Islands, 
Mr. ti. O. Forbes says, they gam their living by forcing other fishing birds 
like the gannets and noddy terns, to disgorge the fishes they have caught' 
Ihe cormorants are large, green-eyed, marine blackbirds. They are 
common along the seashore. They feed chiefly on fish and are gregarious 
Iheir gular pouch is rudimentary as compared with that of the pelican 
Ihe Chinese tame the cormorant and use it in catching fish. The pelican 
IS used for a like purpose in the East Indies. 

The pelicans are large birds, with very large bills and immense gular 
pouches in which they catch the fish upon which they feed. The brown 
pelican (Peleca'nus fus'cus) of Florida is a sociable bird, about 4 feet in 
height. It does not acquire its full colors until its third year. The neck 
ot the adult bird is in two colors, white and a rich blackish brown. The 
back IS a beautiful silvery gray-brown effect composed of many tints. 
Ihe top of the head is white or yellowish, the pouch a bluish purple or 
greenish. The bill is a foot long and demands and supplies four pounds of 
fish each day. Pelican Island, Florida, is the government reservation for 
these birds (Fig. 232). 

The California brown pelican {Peleca'nus calif or'nicus) is found along the 
Pacific coast from Galapagos to British Columbia. The beautiful great 
white pelican (P. erythrorhyn'chos) is now rare. It is found in large western 
inland lakes and in the Yellowstone National Park. The male has a pe- 
culiar knob on the bill during the breeding season only. 

Order V. An'seres.— These birds have flat, lamellated bills 
(Fig. 233). The body is rather flat. The legs are far back on 
the body, causing them to waddle when they walk and making 
them good swimmers. Their toes are webbed. The feathers 
are well oiled so they can go into the water. Geese spend less 
time in the water than ducks do. The food is largely vegetable. 
The swans, geese, and eider duck do not dive in feeding, but 
thrust the head and neck under water, sometimes tipping up the 
body. Marine ducks are expert divers. The wild geese, ducks, 
and brant are migratory, but they are not so numerous as 
formerly, since so many have been slaughtered for market and 
sport 

• 

The swan belongs to this order and is the largest of the Anseres. In 
fact, it IS one of our largest birds. Hornaday says it is pugnacious and 
quarrelsome. The plumage of the trumpeter swan is white; the bill and 
feet are JDlack . The young are a dirty gray. The ' ' voice is like a blast from 
a French horn," but is musical when given by a large flock in chorus. The 
range is from the Gulf to the fur countries. They breed from Iowa north 
and west to the Pacific coast. 



286 



BRANCH CHORDATA 



Order VI. Odontoglos'sae. — The American flamingo, of the 
warm parts of the Atlantic coast, is our representative of this 
order. It is a large, web-footed, long-necked, wading bird. 
The color varies from rose to vermilion. It has a heavy, bent, 
lamellated bill, with which it scoops up and crushes small mol- 
lusks and crustaceans, on which it feeds. Its webbed feet are 
used more for support in walking on the soft mud than for swim- 




Fig. 233. — Ring-necked duck (Aythya collaris); 17 inches. 

men.) 



(From speci- 



ming. Flamingoes nest in colonies. A colony visited by Mr. 
Chapman contained upward of two thousand nests. One or 
two eggs make up a clutch. The voice is a vibrant honking, 
like that of a wild goose. 

Order VII. Hero'diones. — This order is represented by such 
birds as the storks, herons, ibises, and spoon-bills. They are 
long-billed, long-necked, long-legged, wading birds, with short 
tails and broad, rounded wings. They frequent the water and 



WATER BIRDS 



287 



seize their prey, be it fish or frog, with their long sharp bills. 
The young are altricial. 

There are probably twenty species of storks, all but two of which are 
found m the Old World. The migratory stork of Europe is the most famous 
Their clumsy nests are known over the world. 




Fig. 234.— American egret (Ard'ea egret'ta). Length, 41 inches, 
graph from specimen with neck extended.) 



(Photo- 



The herons are variously called the bittern, the great blue heron, the 
green heron, the great white egret, and the "squawk." Many have 
ornamental crests and plumes. Some herons stand in waiting, while 
others run rapidly and noisily through the water, depending on their 
agihty m capturing their prey. Some stalk slowly and silently along in 
shallow water, the head carried in front in a line with the shoulders and 
the large eyes scrutinizing every object in the water. Herons and ibises 
are gregarious, nesting and roosting in flocks, but feeding individually 



288 



BRANCH CHORDATA 



The heronry or rookery is located in low trees on a small island or marsh. 
Bitterns are found singly or in pairs. 

The herons, egrets/ and ibises have been so persistently hunted for their 
plumes that some species are now quite rare. The snowy heron {Ard'ea 
candidis' sima) and the American egret {Ard'ea egret'ta) (Fig. 234) are 
the most beautiful of these. Their black legs and bills only intensify the 




Fig. 235.- 



-Sand-hill crane {Grus mexica'na). 
specimen.) 



Length, 44 inches. (From 



snowy whiteness of their plumage. The filmy aigrettes are like spun glass. 
These number about fifty and are worn by the mother during the breeding 
season only. To obtain these plumes the mother must be shot, and the 
nestlings are left to perish simply to gratify the vanity of thoughtless 
women. The sale of these aigrettes in the United States is now forbidden 
by law. 

1 Apgar's " Birds of the United States." 



WATER BIRDS 



289 



Order VIII. Paludic'olae, as the name indicates, are marsh- 
inhabiting birds. The crane is a famihar example. 

The coot, or mud-hen, is abundant in reedy swamps, near 
small creeks and shallow lakes. It is an excellent swimmer. Its 
foot is scalloped or only half- webbed. It is omnivorous. 

The rails and cranes resemble large or overgrown Limicolce. The young 
are precocial. These birds usually feed on surface materials rather than 




Fig. 



236. — A valuable bird in danger of extinction — field plover, 
book, U. S. Dept. of Agricul., 1907.) 



(Year- 



by probing in the mud, as the plovers and snipes do. The rails are chiefly 
marsh or swamp birds of medium or small size. The Virginia rail is a little 
smaller than a quail. " He is an odd-looking bird, with a half-quizzical, 
half-cynical expression. His eyes are blood red and deeply sunk in the 
long, narrow head." 

The cranes (Fig. 23.5), of which there are but three species in North 
America, are easily distinguished by the long bill, long head, very long neck, 
short, broad wings, short tail, and very long legs. They fly in single file 
with legs and neck outstretched. The cranes resemble the rails in general 
structure, but the herons in external form. 

19 



290 



BRANCH CHORDATA 



The whooping or white crane is now very rare. A full-grown one is 
4j feet high. Hornaday says its trumpet call will carry as far as the roar of 
a lion. The sand-hill or brown crane ranges from the Gulf to Manitoba. 
The nests, of roots, rushes, and weeds, are made on the ground and usually 
contain two eggs. Goss says " during courtship and the early breeding sea- 
son their actions and antics at times are ludicrous in the extreme, bowing 
and leaping high in the air, hopping, skipping, and circling about with 
drooping wings and croaking whoop, an almost indescribable dance and 




Fig. 237. — Long-billed curlew ( Nume'nius longiros'tris) ; 23 inches. (Photo- 
graph from specimen.) 

din, in which the females (an exception to the rule) join, all working them- 
selves up into a fever of excitement only equalled by an Indian war dance, 
and, like the same, it only stops when the last one is exhausted." 



Order IX. Limic'olae. — These are small or medium-sized birds, 
usually brown or gray, with some white in their plumage. The 
bill is long and slender and the legs spindling. Except in a 



LAND BIRDS 291 

few species the tibia is bare of feathers, sometimes almost to the 
knee. With a single exception, the hind toe is short and elevated 
or lacking. There are about 125 species of these shore birds, or, 
as their original name suggests, mud-dwellers, of which 75 live 
in America, north of Mexico. 

The Phal'aropes are small in size and in number of species, of which there 
are but three. These lobe-toed birds have this peculiar characteristic: 
the female, which is larger and more brightly colored than the male, does 
the courting. The male does the incubating and cares for the young, 
which are soon able to swim and to hunt their own food. 

Snipes and plovers (Fig. 236) are much sought for game birds in some 
regions. The young are precocial. They afford some fine examples of 
protective resemblance. One may be very near a snipe and not see it if 
it only keeps still, so perfect is its resemblance to its surroundings. 

The Jack snipe {Gallina'go delica'ta) and the American woodcock 
(Philohe'la minor) have shorter legs and the eyes are farther back on the 
heads than in any other birds. Their long, straight bills have sensitive 
tips, with which they probe down into the mud for earthworms. Horna- 
day describes the shrill cry of the Jack snipe when it rises as a half-scream, 
half -squawk. Its range is large, extending all through the United States, 
except in arid regions. 

The avocet or stilt {Recurviro'stra americana) is like a snipe, but the legs 
and bill are much longer than those of a snipe. 

The curlews (Fig. 237), sandpipers, and oyster-catchers also belong to 
this order. 

A plover {^giali'tis vocif'erd) , commonly called killdeer, is found through- 
out the temperate portion of North America. They are quite common 
birds in the Mississippi Valley. Though scattered when feeding, they fly 
in flocks. 

LAND BIRDS 

Order X. Galli'nae. — This order includes many birds val- 
uable to man, as pheasants, pea-fowls, guineas, chickens, turkeys, 
quails (Fig. 238), and prairie-chickens. The birds of this order 
are chiefly ground birds, living largely on seeds and grains, hence 
the crop and gizzard are well developed. Their bodies are robust, 
their wings rather short, the legs stout, and the feet clawed. 
The bills are short and stout. They are poor jQyers, often going 
with a " whirr." In the wild forms the protective resemblance 
is almost perfect, their colors blending with the grass, brush, and 
weeds in which they live. The ptarmigan (Fig. 239) changes 
color with the season to suit its environment, being white in 
winter. The males of this order usually have conspicuous mark- 
ings on the head, as the rooster's comb and wattle, and the red 
head of the turkey gobblers, or conspicuous plumage, as the pea- 



292 



BRANCH CHORDATA 



cock. They are polygamous. The rivalry is keen and the 
males fight fierce battles. 

The only native bird of the pheasants is the wild turkey, now almost 
exterminated by the sportmen, being found in a few regions of the Eastern 
and Southern States, and in Oklahoma and Texas. Several pheasants have 
been introduced into this country from China. The common chickens are 
descendants of the jungle fowl of India {Gallus hankivus). 

The grouse family all nest on the ground. Their colors are chiefly brown 
and gray, so they rely on concealment for protection. The " whirr " 
accompanying flight is caused by the beating of their small concave wings. 




Fig. 238. — Quail {Coli'nus Virginia' nus) ; 10 inches. 

specimen.) 



(Photograph from 



To this family belong the bob-white or " quail," the sage grouse of the 
West, and the once common prairie-hen of the Mississippi Valley. The 
male prairie-chicken has peculiar salmon-colored air-sacs on the sides of his 
neck which he inflates in making his " bum-bum-boo " as he struts and bows 
to his prospective mate in the courting season. 

Order XI. Colum'bae. — This order is represented in the United 
States by the pigeons and doves. There are about 300 species 
in the world, but only ten or eleven in the United States. The 
head is small and round, the bill and legs short, the body 



LAND BIRDS 



293 



plump, and the plumage has a peculiar iridescence. Some 
live on the ground, others in trees, and still others in open places. 

The ttirtle dove, or mournmg dove, is one of our commonest species and 
its plamtive cooing is quite familiar to all. It breeds throughout the 
United States, and one often meets it in the country roads. It is one of the 
farmer's useful, as well as beautiful, friends. Three stomachs, examined 
at Washington, were found to contain 23,100 weed seeds. 

Darwin says our domestic pigeons originated from the blue-rock pigeon 
(Colutn'ba liv'ia). The nest of the pigeon is a flimsy one of twigs, on which 
it lays two white eggs, from which hatch the naked, altricial " squabs." 



JIuTur- V 




Summer • 



Fig. 239.— Seasonal changes of color in ptarmigan {Lngo'pus wu'tus); 
^ natural size. (Romanes.) 



Both sexes mcubate. The young are fed on " pigeon's milk," the parent 
thrustmg its bill into the mouth of the young and discharging therein 
food which has been softened in its own crop. Chapman and Reed say 
also that some species of pigeons nest in isolated pairs and other species in 
large colonies. If you have ever watched a pigeon drink, you know that it 
holds the bill in the water till it has finished drinking. The Carrier pigeon 
is a variety of the domestic pigeon used to carry messages. The Wild or 
Passenger pigeon (Edopis'tes migrato'rius) was formerly very abundant. 
In 1808 Wilson estimated one flock at over 2,000,000,000 pigeons. They 
are now almost extinct, another result of the hunter and his gun. 

Alhed to the pigeons was the extinct dodo of Madagascar. It was a 
giant compared to our pigeons. Look up a picture of it^ and see what a 
strange looking bird it was. It could not flv. 



1 Evans, "Birds," p. 329. 



294 



BRANCH CHORDATA 



Order XII. Rapto'res. — These are usually large, strong birds, 
with hooked bill and strong claws for seizing and holding their 
prey, which consists of fish, birds, rats, mice, and other small 
mammals. To this order belong hawks, eagles, condors, buz- 
zards, vultures, and owls. 




Fig. 240. — Bald eagle {Halicee'tus leucoceph'alus) (drawn by R. Ridg- 
way); 34 inches. (Bulletin 27, Biological Survey, U. S. Dept. of Agri- 
cul., 1906.) 

The hawks and eagles {Falcon' idije) (Fig. 240) comprise about three hun- 
dred and fifty species and include such birds as the kites, hawks, buzzards, 
and the osprey or fish-hawk. These are almost exclusively carnivorous. 
Raptores are easily distinguished by their hooked bills and sharp talons. 
They feed chiefly on rats and mice. Occasionally some of the hawks will 
attack chickens, but there are more friends than foes among them. Hawks 
build large nests of sticks in tall trees. They lay four whitish eggs with 
brown blotches. 



LAND BIRDS 295 

The sharp-shinned hawk is small (length, llj inches), with a long square 
tail marked by widely separated dark bands across it, the widest one 
nearest the end. The principal food is song birds, so this hawk should be 
destroyed wherever found. Cooper's hawk is dark brown with grayish and 
brownish spotted under parts. Its tail is round. In food habits it is much 
like the sharp-shinned hawk, and it should be destroyed. 

The red-tailed hawk (Fig. 241), more often called the chicken-hawk, is 
a great destroyer of injurious mammals. Poultry and other birds do not 
constitute 10 per cent, of this hawk's food, and all other beneficial animals 
which it eats added do not make 15 per cent. So its record is 85 per cent, 
as a friend, against 15 per cent, as an enemy, of the farmer. 




Fig. 241. — Red-tailed hawk (much reduced). Length, 21 inches. (Bulle- 
tin 17, Biological Survey, 1902.) 

Owls in America north of Mexico number eighteen species. " They vary 
in size from the tiny elf-owl of Arizona (only 6 inches long) to the great gray 
owl of the Arctic regions (30 inches long). The owls (Fig. 242) {Bubon'idce 
and Strig'idoe) have a soft plumage, hence their silent flight. Their eyes are 
large and dilatable, enabling them to see well at night. The face is so 
broad that both eyes look forward. They are immovable, so that to look 
in another direction the head must be turned. They have a peculiar voice, 
a screech in our little screech owl and a " who-hoo-whoo " in the great 
horned owl. When one is camping in the woods the sound of this bird 
gives one queer creepy feelings until one knows what is making it. Owls 
live chiefly on rats, mice, frogs, snakes, and rabbits. Some of the smaller 



296 



BRANCH CHORDATA 



ones devour many grasshoppers and other insects. They regurgitate the 
indigestible portions of their prey in Httle oblong balls or pellets, which may 
be found on the ground under the trees in which they nest. Owls nest in 
holes in trees or banks, and lay from three to five pure white eggs. They 
feed at night when the rats and mice are about. Thus they are of more 
benefit than the day-feeding hawks. 

The great horned owl is the only species which is harmful to man, and 
even it pays something for its chickens with the mice and rats it kills. 
" Mr. O. E. Niles, of Ohio, once found in a nest of this bird several full-grown 




Fig. 242. — Barn owl (Strix pratin'cola) . (Photograph from specimen.) 



Norway rats, and on the ground under the tree containing the nest he found 
the bodies of 113 rats."i Now how many chickens would that number of 
rats eat in a year? Probably more than one great horned owl would eat, 
and a lot of corn besides. The investigations at Washington prove, how- 
ever, that, although many rats and mice are eaten, so many small birds 
and domestic fowls are destroyed by it, that one is justified in shooting the 
great horned owl. 

Burrowing owls (see Prairie dogs) nest in the abandoned nests of prairie 
dogs, but do not live in the same nest with them. 
1 Hornaday, p. 223. 



LAND BIRDS 



297 



Order XIII. Psit'taci. — Parrots or paroquets are usually 
highly colored, harsh-voiced tropical birds, with thick, stout 
bills. The upper half of the bill extends down over the lower one. 
The toes, which are used as hands, or with which they walk or 
climb, are arranged two in front and two behind. There are 
about 500 species of these birds. They live on fruits and seeds. 
They are of considerable commercial importance. The parrot 
is quite a common pet. The Carolina paroquet is the only 
species found native in the United States. Its range formerly 




Fig. 243. — Belted kingfisher {Cer'yle alcyon); 13 inches. (Photographed 

from specimen.) 



extended to the Great Lakes, but now it is found only " rarely 
in Florida and along the Gulf coast to Indian Territory." 

Order XIV. Coc'cyges. — This is an Old World order of trop- 
ical birds, "classified together in one miscellaneous group only 
because they belong to no other order." 

Kingfishers are a large family of about two hundred species, chiefly of 
tropical birds, represented in the United States by three species. The 
belted kingfisher (Fig. 243) is our common species, described by Apgar as 
" a noisy, short-tailed, large, straight-billed, crested, blue-backed bird, with 
white lower parts and a bluish band across the breast." 



298 



BRANCH CHORDATA 



The trogons (fifty species) are brilliantly colored tropical birds. The 
coppery tailed trogon of Texas is our representative. It is said to be the 
most beautiful of North American birds. 

Cuckoos (two hundred species) are tropical birds represented in the 
United States by several species. The rain crow, or yellow-billed cuckoo 
(Fig. 244), is an example. It feeds on the tent caterpillar which infests 
our trees. It is the Old World cuckoo which lays its eggs in the nests of 
other birds, not our American bird. With the species Anis, one nest serves 
for several females and it sometimes contains thirty eggs. The joint owners 
share in the care of the young. 




Fig. 244. — Yellow-billed cuckoo which feeds upon hairy tent caterpillars. 
' (After Brehm.) 



Order XV. Pi'ci. — In our latitude this order includes wood- 
peckers of various kinds and under various common names, such 
as red-headed and downy woodpeckers (Fig. 245) , sap-suckers, 
and flickers or yellow-hammers. All are arboreal, and all, 
except the sap-suckers, are insectivorous. Their toes are 
arranged two in front and two behind, except in a few 
American three-toed woodpeckers. The tail feathers are 
stiff and help to brace the bird as it clings to the trunk of 
a tree and pecks for food. The bill is strong and fitted for 
drilling holes into trees for nests or to procure food. The 
tongue is long, flexible, and spear-tipped, so as to enable the bird 



LAND BIRDS 



299 



to reach a long distance and to spear the larvae of insects, 
on which it delights to feed. The birds of this order are poor 
singers, but good drummers. Everyone has heard the tattoo of 
the woodpecker on the trunk of an old dead tree. The four to 
nine eggs are white, and the nest is placed in a hole high up in 
the tree away from enemies. The young are naked and are 
reared in the nest (altricial) . There are 350 species distributed 




Fig. 245. — The hairy woodpecker at breakfast. 
U. S. Dept. of Agriculture.) 



(Biological Survey, 



throughout the wooded districts of the world, except in Madagas- 
car and Australia. The North American species are not highly 
migratory, but are represented in the northern parts of their 
range throughout the year, since they feed largely on the eggs and 
larvse of boring insects, which they can find all the year. They 
are of great value. Two-thirds or more of the food of the downy 
and hairy woodpeckers consists of noxious insects. 



300 BRANCH CHORDATA 

Order XVI. Machrochi'res. — To this order belongs a group of 
remarkable flyers, such as the humming-bird, chimney-swifts, 
whip-poor-wills, and night-hawks. These birds have long, 
pointed wings. Most of them fly at dusk or at night and feed 
chiefly on insects. 

The humming-birds are tropical or semitropical birds of the New World, 
there being some 400 or 500 species. The hawk or sphynx-moths which 
feed at dusk may be mistaken for humming-birds. Apgar says several 
species are found west of the Rocky Mountains in the United States. The 
ruby throated humming-bird is the one we see about our trumpet-creepers, 
honeysuckle, and salvia, seeking both insects and nectar. Chapman says 
" the young are fed by regurgitation, the parent bird inserting its bill 
into the mouth of its offspring and injecting food as though from a syringe." 
Its note is a mere squeak or prolonged twitter. A humming-bird's nest is 
about the size of a lady's watch, and the two frail, pearly white eggs, like 
large peas, hatch in fourteen days. 

The swifts are widely distributed. They have strong wings. They can 
fly straight up or down and feed on the wing. The legs are so weak that 
some species cling to a vertical surface, using the tail to help support them, 
instead of perching. The tip of each tail feather ends in a sharp point, 
the shaft extending beyond the vane. They nest in hollow trees or chim- 
neys. " The nest of our chimney-swift is a bracket-like basket of small 
twigs gathered while the bird is on the wing, and glued together and to tree 
or chimney by a glutinous saliva." 

The night-hawk resembles the whip-poor-will, and is usually compared 
with it, but it is a bird of the sky, and " its note is a loud nasal peent uttered 
as it flies." It has an enormous mouth fringed above with bristles. It 
eats insects which it catches on the wing. When it alights it chooses a 
nearly horizontal limb on which it sits lengthwise, looking like a big knot. 
It migrates to South America in winter 

The whip-poor-will is well known by its peculiar cry. It feeds on 
insects which it catches at night as it flies. During the day it rests quietly 
on the ground in the woods. 

Order XVII. Pas'seres. — This vast order comprises at least 
half of the birds. They have four toes, three in front and one 
behind, on a level with the front toes. The legs are rather slen- 
der, and so placed on the body as to give it a horizontal position 
when it rests. These are our most common birds. They vary 
in size from the little house wren to the crow. Thrushes, blue- 
birds, kinglets, chickadees, creepers, wrens, wag-tails, warblers, 
vireos, shrikes, wax-wings, swallows, tanagers, sparrows, orioles, 
crows, larks, and fly-catchers are representatives of this order. 
They include some of our finest songsters. Most of them are 
plainly clad, inconspicuous birds, working and singing, often 
unseen. Not all of them, however, are unattractive in ap- 



LAND BIRDS 



301 



pearance, for think of the bobohnk, the magpie, the jay, the 
grosbeak, the tanager, the cardinal, the oriole, and the modest 
little wax-wing. Each brings to one's mind a different type of 
beauty. The temperate zone contains the sweetest singers in all 
the bird world. The great majority of this order live upon insect 
food, wherein lies their greatest value. Others live on weed 
seeds and waste grain, and, lastly, on fruit in its season. 

The fly-catchers {Tyran'nidce) (Fig. 246) are found only in America, 
being especially abundant in the tropics. They number over 350 species. 




Fig. 246.— Phoebe. (Bulletin 17, U. S. Biological Survey, 1902.) 



Of the thirty species that breed here, not more than -a half dozen are 
permanent residents of the temperate region. They feed on insects, mostly 
injurious ones, which they catch while on the wing. 

The true larks (Alau'didce) are chiefly Old World birds, there being about 
100 species in Europe, most notably the skylark. We have only about a 
dozen of this family, the horned and shore larks. The " meadow-lark " 
belongs not in this family, but with the blackbirds. 

Of the crows and jays {Cor'vidoe) we have about twenty-five of the two 
hundred species. They are migratory only to a certain extent, being 
winter residents except in the North. They are omnivorous, eating fruits, 
seeds, insects, and, in some cases, the eggs and young of other birds. This 
last habit is by far their worst one. They have unusual intelligence. 



302 



BRANCH CHORDATA 



The orange and black Baltimore oriole (Fig. 247), one of the most beauti- 
ful, as well as useful, of our summer birds, destroys many tent caterpillars 
and other hairy larvse which few birds will eat. If one has ever known 
his rich, clear whistle, one can never forget it or fail to recognize it when the 
bird arrives about the first week of May. The delicate hanging nest, 
which the female weaves of grass and hair and strings, is a marvelous ac- 
complishment. It is suspended far out near the end of a small flexible 
twig, where cats and boys cannot come. The elm is a favorite nesting tree. 




Fig. 247. — ^Baltimore oriole attacking nest of American tent caterpillar. 
(Bulletin 75, 1900, New Hampshire Coll. Exp. Station.) 



Grackles or blackbirds are common summer residents. They are said 
to have the same bad habit as the jays and crows, of eating the eggs and 
young of other birds, though they eat also many injurious insects. 

The cowbird lays its eggs in the nests of other birds. It should be killed 
and its eggs destroyed. 

The largest family {Fringill'idce) of birds (about 500 species), containing 
the finches, sparrows, and grosbeaks, is represented everywhere except in 
the Australian region. They are chiefly seed-eating (Fig. 248) and so are 
less migratory than insect-eating birds. The sparrows are plain-inhabiting 
and are protectively colored, while the more arboreal grosbeaks and 
finches are rather brilliant. 



LAND BIRDS 



303 





Fig. 248. — Four common seed-destroying sparrows: 1, Junco; 2, white- 
throated sparrow; 3, fox sparrow; 4, true sparrow. (Bulletin 17, Biological 
Survey, U. S. Dept. of Agriculture.) 



304 



BRANCH CHORDATA 



Although the tanagers are distinctively American, only five of them come 
so far north as the United States. They are remarkable for their brilliant 
plumage. When one sees the tanager in his royal or " court costume" one 
feels that this beautiful bird of summer has indeed put brightness into 
that day. Tanagers are arboreal, loving the woods. They feed on 
flowers, fruit, and insects. 

Swallows (Hi'rundin'idoe) have a remarkable power of flight. In 
summer they are found throughout North America. Our barn swallow in 
winter goes as far south as Brazil. The number of injurious and annoying 
insects which they catch on the wing is almost beyond imagination. 

The wax-wings {AmpeV idee) (Fig. 249) are found in the northern parts of 
both the Old and New Worlds, though there are but three species. They 
feed chiefly on wild fruits and insects, including the elm beetle. They are 




Fig. 249. — Cedar wax-wing. (Biological Survey, U. S. Dept. Agricul.) 



usually found in small flocks. Their common notes are a few unmusical 
calls, which our cedar wax-wing usually utters when about to fly.^ The 
quiet beauty of these birds is beyond all description. 

The warblers (MniotU'tidce) are characteristic North American birds 
and number more than 100 species, of which 70 visit the United States. The 
others are tropical. With us in the temperate region they are only birds 
of passage, making us brief but regular visits in May as they go to their 
northern breeding ground, and again in September as they return to the 
southland. Most of them are woodland birds. Some are terrestrial, some 
arboreal, and others are lovers of the thickets. They migrate by night. 
Insects constitute nearly their entire food, and they are among our best 
friends. 

^ Reed and Chapman. 



LAND BIRDS 



305 



The black-masked Maryland yellow throat is one of the tiny warblers 
often seen in the Mississippi Valley. He haunts the thicket. His song, 
" witchery, witchery, witchery," is characteristic of his active, nervous 
energy. 

The little black and white warbler, often called the black and white 
creeper, is about 5 inches long. It is a more active climber than even the 
true creepers, hanging from the under surface of branches and twigs or 
flitting from tree to tree. It is usually silent. Its occasional " see-see-see " 
is thin and wiry. 

The wrens, thrashers, and the mocking-bird (Fig. 250) (Troglodyt'idoe) 
include many fine singers. They are inconspicuously colored birds, feed- 
ing near the ground. Many of them like the low scrubby tangled growth 
so dear to the catbird, which cheers us all the summer day, rain or shine. 
This bird does valiant service as a caterpillar hunter, especially when 
feeding the young. 




Fig. 250. — Mocking-bird. (Biological Survey, U. S. Dept. Agricul.) 

The creepers (Certhi'idce) do good work in keeping down the pests of the 
tree trunks all the year around. 

The nuthatches (Par'idoe) also help in tree keeping, as do our little chick- 
adees, which stay the winter through. 

The thrushes (Tur'didce) are usually fine singers. The best known are 
the much-loved robin and bluebird (Fig. 251). 

There are several other families of Passeres, but lack of space forbids us 
to dwell longer on this fascinating subject. 



Economic Importance. — Millions of dollars' worth of farm 
products are destroyed annually by insect pests, but if these great 
hordes of marauders were not held in check by their natural 
enemies, the birds, the devastation would be so great in a few 
years as to cause actual famine. 

20 



306 



BRANCH CHORDATA 



• Where man has not interfered, nature has a well-balanced 
arrangement for the protection of his crops. The grasses and 
low-growing herbs are protected from such enemies as the cut- 
worm, caterpillar, and grasshopper by the chipping sparrow, 
robin, and bluebird, and, farther afield, by the quail, meadow- 
lark, blackbird, and field sparrow. In the edge of the woods are 




Fig. 251. — Bluebird at edge of nest with grasshopper in mouth. (From 
photograph by Rev. P. B. Peabody.) (Bulletin 17, Biological Survey, 
U. S. Dept. of Agriculture.) 



the chewinks and brown thrashers; and in the deep woods, the 
ruffed grouse ; while along the fresh-water streams and ponds may 
be seen the woodcocks, sandpipers, and snipes. In the trees 
"the woodpeckers, assisted by the nuthatches and creepers, 
look after insects on and beneath the bark of both the trunk and 
the branches."^ The chickadees, bluebirds, thrushes, warblers, 

1 Weed and Dearborn, " Birds in Their Relation to Man.'' 



LAND BIRDS 



307 



vireos, kinglets, and many more guard the leaves. The insects 
of the air are preyed upon in the daytime by the diurnal birds, 
such as the swallows, swifts, kingbirds, and fly-catchers. Cre- 
puscular insects are caught by such birds as the whip-poor- 
will, night-hawk, and small owls. 

Hawks and owls destroy many rats and mice and other young 
rodents, while the vultures are very useful as scavangers, since 
they subsist largely on carrion. The South African secretary 
bird (Fig. 252) belongs in the list of friends. 







Fig. 252. — Secretary bird (Gypoger'anus reptiliv'orus) . A South African 
snake-killer protected by law. (After Houssay.) 



Certain kinds of birds are of especially great value on account 
of their specific food, insect pests which are making such havoc 
with particular crops or with certain trees. Thus, the swallows, 
which eat almost nothing of value to man, prey upon the cotton- 
boll weevil, which they catch upon the wing. Forty-seven adult 
weevils have been found in the stomach of a single swallow. It 
should be remembered that the swallows, which are such inde- 
fatigable insect destroyers here in the breeding season, migrate 



308 



BRANCH CHORDATA 



to the South and are of great specific value there by reason of their 
raids upon the cotton-boll weevil, so they should be encouraged 

and protected from the English 
sparrow. Orioles do royal service 
in catching weevils on the bolls. 
Blackbirds, wrens, and fly-catchers 
do good work. 

Sparrows prey upon the green 
wheat aphid of North CaroHna. 

During an outbreak of canker- 
worm in a central Illinois apple 
orchard the investigations of Prof. 
S. A. Forbes showed that the food 
of robins, catbirds, brown thrashers, 
and bluebirds consisted of 96 per 
cent, insects, of which 16 per cent. 
was cankerworms, while the food of 
the house wrens he examined was 
50 per cent, cankerworms; 25 per 
cent, of the food of the hairy and 
downy woodpeckers consists of bor- 
ing larvae. 

It is true that birds eat a certain 
percentage of fruit and seeds, but 
the entire amount of vegetable 
matter is usually much less than 
the animal matter consumed. A 
large proportion of the seeds eaten 
are weed seeds (Fig. 253), such as 
dandelion, dock, knot-weed, purs- 
lane, pigeon-grass, and rag-weed.^ 
The grain which birds eat is, much 
of it, picked up from the waste 
matter about the farm-yard. 
Doctor Judd^ says the great horned owl, the sharp-shinned 
and Cooper hawk, and the English sparrow are injurious birds 




Fig. 253.— Weed seeds 
commonly eaten by birds: 
a, Birdweed; b, lambs' quar- 
ter; c, purslane; d, amaranth; 
e, spotted spurge ; /, ragweed ; 
g, pigeon grass; h, dandelion. 
(Biological Survey, U. S. 
Dept. Agricul.) 



^ Jackson and Daugherty, 
School Garden." 

2 Linville and Kelly. 



Agriculture through the Laboratory and 



LAND BIRDS 309 

and should be killed. The cowbird should be added to this list, 
since it lays its eggs in the nests of smaller birds. When this 
hatches, it deprives their young of room and care, often pushing 
them out of the nest, or taking their food and allowing them to 
starve. The blackbirds and jaybirds are questionable charac- 
ters, since they are so mean about robbing nests and driving 
away other birds. The protection of all but the few birds named 
should be emphasized, especially by all farmers and fruit growers. 

The useless destruction of bird life every year is alarming. 
Besides the thousands on thousands killed for food, there are 
thousands of others killed by the plume-hunters to gratify the 
foolish pride of thoughtless, silly women. Much as this is to be 
deprecated, it slaughters but one-fifth as many birds as those 
killed by men and boys for the mere sport of killing. Surely 
the killing for the love of it, many times leaving the birds to 
decay where they have been shot, perhaps only wounded and 
left to die by a slow torture of starvation, is a cruel and sense- 
less practice, yet fully one-half of all the birds killed in the United 
States are killed merely for sport. ^ 

Surely it is time to stop and think; time to teach the coming 
generation the value of birds to human life; time to teach the 
boys and girls to love the birds and to study their habits, so as to 
learn which are friends and which foes. Girls should learn that 
a dead bird upon the hat, no matter how beautiful, is a mark of 
the heartlessness of the wearer. Boys should be taught to shoot 
birds with a camera, not with a gun. It takes far more intelli- 
gence and skill and will be found a more fascinating sport. 

Laws are being made in many states for bird protection. The 
United States Government is making bird reservations, such as 
Pelican Island, off the coast of Florida; Breton Island, Louisiana; 
Stump Lake, North Dakota, and Yellowstone Lake in the 
National Park. 

Geographic Distribution. — Birds as a class are the most 
widely distributed of all animals. They are at home in the 
frozen regions of the North or in the dense shades of the tropics, 
upon the rocky steeps of the mountains, or out on the ocean far 
from sight of land. Their wide range of variation in structure 
and habits renders them, as a class, able to adapt themselves to 
1 Hornaday, p. 172. 



310 



BRANCH CHORDATA 



all climates, and their mode of locomotion makes them less re- 
stricted by barriers. 

Important Biologic Facts. — Birds have, in common with 
reptiles, the quadrate bone, and but one occipital condyle. 
They are wonderfully adapted to their aerial mode of life by 
their feathers, by the modifications of the fore limbs into wings, 
and by the air-filled cavity of the bones. Birds are warm- 
blooded (homoiothermal) , the heart being completely divided 
into right and left halves. The fusion of the bones of the hand 
and the tibiotarsus and the tarsometatarsus are peculiar to 
birds. Nest building, as well as incubation, is peculiar to this 
class, though, in rare instances, fishes build nests and' reptiles 
practice incubation. 



Classification.- 


- 


' 


Division 








A. Rati'tse. 




Ostrich, Rhea, etc. 


B. Carina'tae. 






Order 


I. 


Pygop'odes. 


Grebes, Auks, and Loons. 


Order 


II. 


Longipen'nes. 


Gulls, Terns. 


Order 


III. 


Tubina'res. 


Albatross, Petrel. 


Order 


IV. 


Steganop'odes 


. Cormorants, Pelicans. 


Order 


V. 


An'seres. 


Ducks, Geese, and Swans. 


Order 


VI. 


Odontoglos'sse 


. Flamingoes. 


Order 


VII. 


Hero'diones. 


Herons, Storks, Ibises. 


Order 


VIII. 


Paludic'olse. 


Cranes, Rails. 


Order 


IX. 


Limic'olse. 


Snipes, Plovers. 


Order 


X. 


Galli'nse. 


Quails, Grouse, and Chickens. 


Order 


XL 


Colum'bse. 


Doves, Pigeons. 


Order 


XII. 


Rapto'res. 


Hawks, Owls. 


Order 


XIII. 


Psit'taci. 


Parrots. 


Order 


XIV. 


Coc'cyges. 


Cuckoos, Kingfishers. 


Order 


XV. 


Pi'ci. 


Woodpeckers. 


Order 


XVI. 


Macrochi'res. 


Swifts, Humming-birds. 


Order XVII. 


Pas'seres 


All our most common small 



(Perching birds), birds. 



MAMMALIA 311 



CLASS VI. MAMMALLA 



Mammals are homoiothermal, bilaterally symmetric, air- 
breathing, usually hairy chordates. They are, as a rule, 
viviparous and suckle their young. They vary in size from the 
tiny little harvest mouse, probably less than 5 inches long, to 
the great sulphur whale, weighing many tons. Not all of them, 
however, are widely distributed, but everywhere, save in a few 
of the South Sea Islands, some of the several thousand species 
are found. 

Covering. — No other characteristic is more rightfully called 
a distinguishing characteristic than the hair of mammals. 
True hair is found on no other vertebrate. It is general to find 
a hairy covering among mammals. Even among the Cetacea 
hairs are sometimes found upon the muzzle, and traces of hair 
are sometimes found in the embryo. The skin of the whale is 
underlaid by a layer of fat or blubber, while that of those un- 
gulates that are sparsely covered with hair, as the rhinoceros, 
is very thick. The hair may differ greatly both in length and 
texture. It may be soft and kinky "wool" or very fine fur. 
The coarse hairs may become long, hard bristles, like those of 
the hog, or be differentiated into stiff " spines," like those of 
the porcupine, or into a scale armor, like that of the armadillo. 

Sweat glands in the skin are also characteristic of mammals. 

The skeleton is the most nearly perfect of any of the chordates. 
The skull (Fig. 254) is composed of fewer bones more firmly 
united than in the lower chordates. The lower jaw is composed 
of a single bone on each side, the dentary, and is articulated 
directly with the squamosal. The skull is connected with the 
first vertebra, the atlas, by two occipital condyles instead of one, 
as in the birds and reptiles. 

The spinal column (Fig. 255) consists of a varying number of 
vertebrae, the first two, the atlas and axis, being somewhat modi- 
fied to support the head and to permit its various movements. 
The vertebrae do not articulate with one another by cup and 
ball (except in some ungulates), as in amphibians, reptiles, and 
birds, since the intervertebral disks of fibrocartilage permit 
lateral bending of the spine. The vertebrae are classified, ac- 
cording to their location, as cervical, dorsal, lumbar, sacral, 



312 



BRANCH CHORDATA 



and caudal. The cervical or neck vertebrae are nearly always 
seven (there are six in the manatee, and six, eight, or nine in 
some of the sloths) . So the length of the neck depends upon the 
length, not the number, of the vertebrae. The dorsal vertebrae 
carry ribs and vary in number (from nine in Hypero'odon^ to 



Mr IT Na 




Fig. 254. — Skull of a dog, side view, with the right half of the mandible 
or lower jaw and hyoid arch, the lower jaw displaced downward to show 
its whole form. (Reduced), an, Anterior narial aperture; ikf T", maxillo- 
turbinal bone; ET, ethmoturbinal; Na, nasal; ME, ossified portion of the 
mesethmoid; CE, cribriform plate of the ethmoturbinal; Fr, frontal; 
Pa, parietal; IP, interparietal; 80, supra-occipital; ExO, exoccipital; 
BO, basi-occipital; Per, periotic; BS, basisphenoid ; Pi, pterygoid; AS, 
alisphenoid; OS, orbitosphenoid; PS, presphenoid; PI, palatine; Yo, 
vomer; Mx, maxilla; PMx, premaxilla {sh, stylohyal; eh, epihyal; ch, cera- 
tohyal; hh, basihyal; th, thyrohyal) equal the right half of the hyoidean 
apparatus; s, symphysis of the mandible; cp, coronoid process; cd, condyle; 
a, angle; id, inferior dental canal; *, the part of the cranium to which the 
condyle is articulated. (After Tenney.) 



twenty-two in Hyrax). The lumbar vertebrae also vary in 
number, usually inversely, as the dorsal, their sum being rather 
constant. The sacral vertebrae are fused together. They are 
absent in Ceta'cea and Sire'nia, where there are no functional 
hind limbs. The caudal vertebrae vary from three to fifty. 
1 Beddard's " Mammalia," p. 23. 



Mammalia 



313 




Fig. 255.— Skull and spinal col- 
umn and single vertebra of a com- 
mon cotton-tail rabbit {Le'pus syl- 
vat'icus) . (Cleaned and mounted by 
students.) 



Fig. 256.— Pelvic girdle of Jack-rab- 
bit. (From dissection.) 



All mammals have ribs. They var,y in number in different 
groups, or, it may be, in different species. The greater number 



314 



BRANCH CHORDATA 



of them are attached anteriorly to the sternum, which is always 
present, and posteriorly to the vertebrae, but there are also a 
number of floating ribs or those attached posteriorly only. 

The pectoral girdle consists of two bones on each side, the 
scapula (Fig. 257) and the clavicle. The clavicle is absent 
in ungulates, which use their fore limbs mainly for support and 
in walking, but it is well developed in " flying," digging, or 
burrowing mammals. 




Fig. 257. — Anterior limb of man, dog, hog, sheep, and horse: Sc, Shoulder- 
blade; c, coracoid; a, b, bones of forearm; 5, bones of the wrist; 6, bones of 
the hand; 7, bones of the fingers. (Le Conte's "Geology," American 
Book Co., Publishers.) 

The pelvic girdle (Fig. 256) consists, normally, of the os in- 
nominatum on each side. There are "four distinct elements in 
each one: the ischium, the ilium, the pubis, and the cotyloid."^ 

The limbs which raise the body from the ground and are the 
principal organs of locomotion are four in number, except in 
Sire'nia and Cetacea, where there are no externally visible hind 
limbs. Rudiments of the pelvis are found in both of these orders, 
and in some of the Cetacea rudiments of the femur and of the 
tibia. The bones of both anterior and posterior limbs (Figs. 257, 

1 Beddard, " Mammalia," p. 41. 



MAMMALIA 



315 



258) vary in size, shape, and number, depending on the en- 
vironmental habits. In all but the Cetacea the ends of the digits 
are protected by horny epidermal coverings, variously termed 
hoofs, nails, or claws. Rudiments of these are found in the 
embryos of the Cetacea, thus suggesting their terrestrial origin. 
The Digestive Organs. — One of the peculiarities of the 
digestive organs in mammals is the development of the salivary 
glands. The teeth are "heterodont" (Fig. 254) instead of 
"homodont," as in some of the lower classes of chordates. 




Fig. 258. — Posterior limb of man, monkey, dog, sheep, and horse: 1, Hip- 
joint; 2, thigh bone; 3, knee-joint; 4, bones of leg; 5, ankle-joint; 6, bones 
of foot; 7, bones of toes. (Le Conte's "Geology," American Book Co., 
Publishers.) 

Some mammals have no teeth, at least not in the adult stage. 
The teeth are attached to the premaxillary, maxillary, and den- 
tary bones, and to no others. These heterodont teeth may be 
classed as incisors, canines, premolars, and molars. The teeth 
would indicate an omnivorous feeding habit, but this is not true 
for all mammals. Some are omnivorous, some carnivorous, and 
many herbivorous. The teeth often give a hint as to the feed- 
ing habits, as well as proving an important element in classifica- 
tion. 



316 BRANCH CHORDATA 

The mouth is generally characterized by thick and fleshy lips, 
which serve as organs of prehension to grasp the food, as does 
also the tongue, the latter being also the seat of the sense of 
taste. 

Owing also to the varying feeding habits, the different organs 
of digestion vary in size; for example, the intestine, which is 
longer in mammals than in any other chordate, is, in the rumi- 
nants, ten times the length of the animal, while in the carnivora 
it is only three or four times as long. At the junction of the 
small with the large intestine there is a blind tube or cecum, 
which is especially developed in most of the vegetable feeders. 

The Circulatory System. — The heart is composed of four 
parts: two ventricles and two auricles. The circulation is 
double, closed, and complete. The left aortic arch is present 
instead of the right aortic arch, as in birds. "There are two 
features in the venous system which distinguish all mammals 
(except Echidna) from the lower chordates. The hepatic portal 
system is limited to a vein which conveys to the liver blood 
derived from the alimentary tract; in no mammal (except in 
Echidna) is there any representative of the anterior abdominal 
vein of the lower vertebrates. ... In no mammal is there any 
trace of a renal portal system. The kidneys derive their blood 
from the renal arteries only."^ 

The red corpuscles of the blood of mammals differ from those 
of other chordates in being much smaller, non-nucleated, cir- 
cular, and biconcave, except in the camel, in which they are 
elliptic. 

The Respiratory System. — No mammals have external gills, 
but all breathe by means of lungs throughout life. Respiration 
is aided by a diaphragm or muscular partition, which com- 
pletely divides the body cavity, separating the heart and lungs 
from the abdominal viscera. When this muscular diaphragm 
contracts its upper surface becomes more concave, increasing 
the lung cavity and allowing the lungs to expand under the pres- 
sure of the air. When the muscles relax the upper surface again 
becomes convex and the lung cavity is reduced, thus forcing out 
the air of the lungs. 

The soft palate and the epiglottis are structures peculiar to 
1 Beddard, p. 88. 



MAMMALIA 



317 



mammals. The vocal organs are in the upper part of the trachea 

instead of the lower, as in birds. 




Fig. 259.— a, Brain of rabbit, from above; the roof of the right hemi- 
sphere IS removed so as to expose the lateral ventricle; b, the same from 
below; c, bram of cat; on the right side the lateral and posterior part of the 
hemisphere is removed, and almost as much on the left side, and the greater 
part of the hemispheres of the cerebellum have been removed ; d, brain of 
orang (a, b, c, after Gegenbaur; d, from the regne animal): Vh, Cerebral 
hemispheres; Mh, corpus quadrigeminum; Cb, cerebellum; Mo, medulla 
oblongata; Lo, olfactory lobe; //, optic nerve; F, trigeminal; VII, VIII, 
facial and auditory nerves; H, hypophosis cerebri; Th, optic thalamus: 
Sr, sinus rhomboidalis. (After Glaus.) 



The Nervous System. — The brain is relatively larger in 
mammals than in other chordates. The cerebral hemispheres 



318 



BRANCH CHORDATA 



are especially developed and are connected by the corpus cal- 
losum, which is not present in birds. The brain (Fig. 259), with 
a few exceptions, is convoluted. 

The special senses are all present except in some Cetacea, 
where the olfactory membrane is degenerate and the sense of 
smell is lacking. The organs of sight and hearing (Fig. 260) 
vary most, owing to the different environments and consequent 
habits and needs of the various species. The sense of touch, 
while distributed over the surface of the body, is especially 




Fig. 260. — Diagram of the labyrinth of the ear in /, the fish; //, the bird; 
and III, a mammal: U, Utriculus; D, sacculus; US, utriculus and sac- 
culus; Cr, canalis reuniens; R, recessus labyrinthi; UC, commencement of 
the cochlea, C, L, lagena ; K, cecal sac at the apex ; C, cecal sac of the ves- 
tibulum of the cochlear canal. (After Waldeyer, from Gegenbaur.) 



sensitive at the ends of the fingers, on the lips, tongue or snout, 
and, in some monkeys, upon the under surface of the tail. The 
cat has long sensitive hairs (vihrissce) connected with nerve-end- 
ings, which are tactile in function. The sense of taste, situated 
on the base and tip of the tongue and on the soft palate, is more 
highly developed than in any other class. 

The sense of scent or smell is highly developed. Correlated 
with the development of smell is the presence of odoriferous 
glands in many mammals. The odors may serve for recognition, 



MAMMALIA 



319 



for warning, or for protection by mimicking the odors of a more 
formidable foe; as the odor of the musk deer may suggest that of 
a crocodile. 

It is readily seen that the nervous system is the highest and 
most complicated of any chordate's, thus giving mammals 
highest rank in the scale of intelligence. 

Order I. Monotrem'ata. — The animals of this order are 
primitive mammals, but that they are mammals is proved by 
the fact that they are covered with hair and nourish their young 
with milk. The heart has an incomplete auriculoventricular 
valve. The temperature is lower and more variable than in 
the higher mammals.^ The brain has no corpus callosum. Like 
birds and reptiles, they are oviparous, and the intestines open 
into a cloaca. These animals are characterized by a temporary 




Fig. 261. — A spiny ant-eater. (From Claus.) 

" mammary pouch," in which they are hatched or to which they 
are transferred after hatching, and into which open the ducts of 
the mammary gland. 



The spiny ant-eater {Echid'na aculea'ta) (Fig. 261) is a small nocturnal 
animal about the size of a duck-bill. It is covered with spines mingled 
with hairs. When danger threatens it curls up like a hedge-hog. Its 
legs are short and stout, and its feet are armed with strong claws for tearing 
open ant-hills. Its tail is vestigial. It has a long, pointed, toothless snout 
and a long, extensible tongue for licking up ants, other insects, and worms. 
The salivary glands are very highly developed, and when the tongue, cover- 
ered with sticky saliva, is thrust into an ant-hill, it is soon covered with the 
insects. The tongue is then drawn back into the mouth and the adhering 
insects swallowed. It seems that the mother places the egg in the mammary 
pouch with her mouth. When the young is hatched it is nourished with 
milk. When it attains sufficient growth she removes it from the pouch, re- 
placing it from time to time for nourishment. She shows further intelli- 
gence by digging a burrow and concealing her young in it when she goes out 

1 Beddard, p. 112. 



320 



BEANCH CHORDATA 



at night for food. An allied form, the nodiak, is eaten by the aborigines 
of the Papuan region. 

The duck-bill (Ornithoryn' chus) (Fig. 262) is found in southern and 
eastern Australia and Tasmania. It has a small, round head, and a 
broad, flattened, sensitive bill. Its eyes are small and somewhat hidden, 
but well developed. Its great paddling feet are five toed and webbed, the 
webs of the anterior feet being longer than the claws. It is about the size of 
our common rabbit and has short legs and a flattened tail. Its body is 
covered with loose skin, protected by thick, glossy hair, with an under layer 
of fine waterproof fur. The duck-bill is aquatic, digging burrows 30 or 40 
feet long in the banks of streams. One opening of this burrow is below the 
water. It dives, enters this opening, and is safe from, its enemies. It has 
teeth when young, but soon sheds them, and the gums harden into horny 
plates for crushing insects, worms, snails, and mussels, which it digs out of 
the mud with its snout and stores away in its cheek pouches to be eaten as 




Fig. 262. — Duck-bill {Ornilhorhynchuii paradoxus). (From Ltitken.) 

it drifts upon the water. Sight and hearing are acute, but it has no external 
ears. The male is armed with a strong horny spur on each hind foot, 
which is connected with a poison gland. The duck-bill is as shy as a beaver. 
Its voice is like the growl of a puppy. The young are blind and naked. 



Order II. Marsupia'lia. — Marsupials are fur-covered, terres- 
trial (rarely aquatic), or arboreal, or subterranean mammals, 
which carry the young, born immature, naked, and blind, at- 
tached to the mammary gland in an abdominal integumentary 
pouch. The milk is forced down the throat of the young by 
the muscular action of the mother. The young are able to 
breathe at the same time by the wrapping of the soft palate 
around the upper end of the trachea in such a manner that the 
air may pass from the nose down the trachea while the milk 
passes down the throat. The clavicle is present. The cloaca 



MAMMALIA 



321 



is reduced. The corpus callosum, if present, is rudimenatry. 
Parameles possess a true allantoic placenta. Many thousand 
skins of the opossums are used yearly. The hair is used in 
making hats and felt. The fur and leather of the kangaroo 
are also used. 

The opossum family {DideV phidce) consists of pendactylous, plantigrade 
marsupials. The pouch is present or absent according to the species. The 
great toe is large and separable from the others, making the foot prehensile. 
The tail is long, prehensile, and usually covered by a scaly skin and a few 
scattered hairs. There are two distinct genera. The first has been divided 
into several by some authors. 




Fig. 263. — The female of Didel'phys dorsig'era, one of the South American 
opossums, carrying its young upon its back. (After Nicholson.) 



Genus Didelphys comprises twenty-three species, most of which are 
tropical, being found in Mexico, Central America, and Brazil, but never in 
Austraha. It is represented in the United States by the common opossum 
{Didel'phus virginia'na). Its habit of feigning death or "playing 'possum " 
when confronted by an enemy is well known. It is about the size of a 
large cat. Its nose is pointed, its eyes and ears large. It is arboreal and 
nocturnal. It eats anything from insects to small reptiles and birds, and 
also devours muskmelons and certain mushrooms; indeed, it is almost 
omnivorous. It does not hibernate. Its young are about J inch in length 
and are carried in the pouch for about eight weeks. After this, in some 
species, they are carried on the back (Fig. 263), their tails interlocking 
with that of the mother. 

Tasmanian marsupials (family Dasyur'idoe) are distinguished from the 
American opossum by fewer incisor teeth, a rudimentary first digit on the 
fore and hind feet, by the absence of a cecum, and by a non-prehensile tail. 
21 



322 BRANCH CHORDATA 

The Tasmanian wolf has a skull like a dog's, and is like the ordinary wolf 
in size, build, and habits. It is of a dusky hue and marked upon the hind 
parts with blackish bands. The hallux is wanting. The "Tasmanian 
devil " is black with white patches on the body. It is the size of a badger 
and its voice is a yelling growl. 

The Australian ant-eater is of a bright reddish color, banded posteriorly 
and dorsally with white, and looks much hke a large red squirrel. It feeds 
upon ants, which it captures with its tongue. Its habitat is both terrestrial 
and arboreal. The young are nourished as in other marsupials, but the 
pouch is lacking, and they are concealed only by the long hair of the 
mother. 

The Australian mole has somewhat the appearance and habits of our 
common mole. It is pale golden red, in harmony with the arid soil in which 
it lives. The claws of the third and fourth front toes are enlarged. "It 
is not only blind, but its eyes have been more completely lost by degenera- 
tion than in any other known case. Its anatomy abounds in curious 
adaptations to an underground existence, evidently antique." 

The Wombats. — There are three species, one Tasmanian and two Aus- 
tralian. Cheek pouches and tail are rudimentary. They are heavily 
built animals, like the badger or marmot, with a shuffling gait. They are 
gregarious, live in burrows, and feed upon roots. They are gentle, but 
stupid. Over a hundred thousand skins are sold in London yearly. 

Several of the smaller species of family Phalanger'idoe are called "flying 
phalangers." They cannot fly upward, of course, but are supported by 
a parachute-like membrane from fore to hind limb, as they descend with a 
sort of skimming or sailing movement. The tail is usually long and pre- 
hensile, and the thumb opposable and nailless. 

The Kangaroos (Macropod'idce) are herbivorous marsupials of Australia 
and the surrounding islands (Fig. 264). They have three incisors on each 
side of the upper jaw and one on each side of the lower. The lower pair 
of incisors are sharp on the inner edge, and to some extent may be moved 
toward and from each other, cutting grass like shears. The fourth toe of 
the hind foot is exceedingly long and strong, and the fifth nearly as strong, 
but shorter, while the third digits are syndactylous,^ but so slender that 
they are of no use in supporting the body. The fore limbs are short and 
small and are used only for grasping. With the exception of Dendrol'agus, 
which is arboreal and has less difference in the length of fore and hind limbs, 
this family is terrestrial. Locomotion consists of a series of leaps, effected 
by the long limbs and the long and powerful tail.^ They vary in size from 
that of a rabbit to giant forms 5 or 6 feet in height. The larva^ of a large 
kangaroo is not over 3 inches in length. They are gregarious, the droves 
numbering from 50 to 150. They are crepuscular, nocturnal, and herbiv- 
orous. They are timid, shy, and harmless if unmolested, but they cap rip 
open a dog with their strong hind claw when necessary to defend themselves. 
When wounded they take to water, and if they get hold of a dog, they under- 
take to drown it. 

Genus Mac'ropus includes kangaroos and wallabies, making together 
twenty-three species. Macro-pus rufus attains the height of 5 feet, 5 

1 See Glossary. 

2 Some authorities state that the tail is not used in rapid locomotion, 
but we know from observation of the kangaroo in the Zoological Gardens 
that it does rest upon the tail between successive leaps in slow locomotion, 

3 Beddard, p. 124. 



MAMMALIA 



323 



inches, not including the tail. M. gigantius is reported by Sir Joseph Banks 
as good for food. It is said that a large kangaroo in rapid flight leaps 20 to 
30 feet at a bound. The female will weigh 120 pounds, some old males weigh 
200 pounds. The smaller species of kangaroos furnish the most fur and 
leather and the best venison. About 350,000 are sold in London annually. 
Rock wallabies (genus Petrog'ale) have a shorter claw on the hind foot 
and a more slender tail, which is thickly covered with hair and never used in 
locomotion (Fig. 264). The tail is used as a balancer, as they leap from 




Fig 264. — Fetrogale xanthopus. The rock wallaby, with young in pouch. 
(After Vogt and Specht.) 

rock to rock. They are found in Australia only. The nocturnal genus 
{Bettongia) and others have sometimes been inaccurately called " rat 
kangaroos." The four species are subterranean, with prehensile tails, 
with which they carry their food, grass, roots, and leaves. One species 
burrows to a depth of 10 feet. It is found in Tasmania and Australia. 



Order III. Edenta'ta. — The five families of this order are 
arboreal, terrestrial, or subterranean, with clawed limbs. They 



324 BRANCH CHORDATA 

are chiefly tropical. The name, Edentata, is somewhat mislead- 
ing, as teeth are not wholly lacking, except in the family Myrme- 
cophag'idoB and the African genus Manis, which, having no use 
for teeth, have lost them. Front teeth are always lacking in this 
order. None of the teeth in the adult have enamel. They are 
said to be stupid and sluggish creatures, and, except in the ant- 
eaters, the brain is devoid of convolutions. 

Ant-eaters {Myrmecophag'idoe). — This family consists of three South 
American genera, all without teeth and with long protrusible, viscid tongues, 
the salivary glands being highly developed. The snout is long and the body 
covered with long hair, while the tail is long and bushy. The claws are 
long and powerful, enabling them to tear open the ant-hills, or, in the ar- 
boreal fornis {Taman'dua and Cyclotu'rus), to tear the bark from trees and 
search for insects or to defend themselves. 

The great ant-eater (Myrmecophaga jubata) is said not to "fear the 
presence of the serpent's fold or the teeth of the jaguar," and will rip 
open a big dog with its claws before the dog's teeth can make an impression 
through the shaggy hair. Including the tail, this species may reach a 
length of 6 or 7 feet. The tail is 2 feet long and said to be the largest of 
that of any mammal. The great ant-eater sleeps through the day in a kind 
of " lair" in the tall grass, where it lies " on one side with its head buried 
in the long fur of the chest, the legs folded together, and the huge tail 
curled. around the exposed side of the body."^ They are numerous in 
their region, although the mother produces but one each year. The young 
stays with the mother a year, riding on her back when little. 

The sloths (Bradypod'idce) , of South America, are arboreal forms, with 
very long anterior limbs, short tails, and round heads. Instead of the usual 
seven cervical vertebrae, the three-toed sloth (Brad'ypus) or " Ai," so called 
from its plaintive cry, has the unusual number of nine, while the two-toed 
genus {Choloe'p-us) has the exceptional number of six. The toes have long, 
recurved, non-retractile claws for clinging to the branches of trees. The feet 
are like hooks with the fingers bent under them, hence they walk slowly 
and clumsily on the ground, but climb about with ease in the trees, where 
they live continually day and night, hanging back downward, even in sleep, 
from the lower side of the limb. They never descend to the ground unless 
compelled to do so, but spring from tree to tree in search of food, which con- 
sists of leaves and green shoots. They are nocturnal. Their hair is long 
and shaggy and covered with minute green algae, giving the animal an al- 
most perfect resemblance to a lichen-covered branch. This may be taken 
as an example of commensalism between animals and plants. 

Armadillos {Dasypod'idoe). — There are several genera of armadillos (Fig, 
265), and they are found chiefly in South America. They are also known 
in Central America, and one species is said to occur in Texas. They are the 
only mammals in which the dermis develops into hard bony plates like those 
of the turtle, while the hair on the dorsal part of the body is replaced by 
horny scales covering the bony plate. 

" Traces of dermal armature exist in one or two genera of the whales."^ 



^ Ingersoll, p. 471. 
2 Beddardj p, 173. 



MAMMALIA 



325 



The different forms are distinguished chiefly by the number of the movable 
bands of " scutes " between the anterior and posterior shields. The little 
Chlamydoph'orus, of about 5 inches in length, has no movable bands at all, 
the series of plates being uniform and continuous even to the neck. The con- 
spicuous external ears so prevalent among the armadillos are also absent. 
Tolypeu'tes can roll itself up into a ball and be protected by its armor, or 
roll away from its enemies. Its walking is digitigrade and it is called 
"pig-footed." Armadillos are orftnivorous, and one species {Das'ypus 
sexcinc'tus) is especially fond of carrion, burrowing up to a carcass like bee- 
tles. The limbs of armadillos are short, powerful, and clawed, enabling 
them to dig rapidly in the ground. 




Fig. 265. — Nine-banded armadillo {Das'ypus novemcinc'tus). (Ltitken.) 

Order IV. Sire'nia. — These are dark-colored, sparsely haired 
or bristly, toothed, herbivorous mammals. The elongated 
snout of the whale is replaced by large movable lips for grasping 
the food, which consists of seaweed and other aquatic plants. 
External ears and hind limbs are absent. The anterior limbs 
are flipper-like, but more flexible than those of the whale, and 
the mother sometimes holds the young under her arm. The tail 
is horizontal. Sirenia grow to a length of 9 or 10 feet. They 
have two sets of heterodont teeth. 

The dugong (Fig. 266) is sparsely covered with stout hairs. 
The thick skin is underlaid with blubber. It is found on the 
east coast of Africa, in the Indian Ocean, and the north coast of 
Australia, and in the Red Sea. 

The manatee is found on the Atlantic coast of South America 
and of Africa, and in the mouths of the large rivers of these 
countries. The blubber in the manatee differs from that of the 
whale in that it has no free oil. 

Steller^s sea-cow, the recently extinct^ Rhyti'na, was found in 
herds in Behring Sea. It reached a length of 20 to 30 feet. The 
flesh was good for food, and the hide and oil of value. 

1 "About 1768 because its fearlessness enabled hunters to kill it easily." — 
Hegner. 



326 



BRANCH CHORDATA 



Order V. Ceta'cea. — The whales must be regarded as true 
mammals, since they nourish their young with milk. They are, 
however, hairless, with the exception of a small number of hairs 
about the muzzle in some species. They are perfectly aquatic, 
never leaving the water. Their form is fish-like, with a large 
and powerful tail horizontally flattened, with a fluke on each 
side. The tail is the chief organ of locomotion, moving up and 
down in a sort of rotary motion, and thus propelling the animal 
from place to place.^ 



/^~ 









z. 




Fig. 266. — The dugong. (From Brehm.) 



The fore limbs are fin-like paddles or flippers and are used as 
balancers. Whales have lost all external trace of hind limbs, 
but a pair of small vestigial bones is found embedded in the 
body. A fleshy dorsal fin is generally present. 

Whales (Fig. 267) are distinguished by a great rounded cra- 
nium, the elongation of jaws and face, and by a prow-like snout 
of fat for the defense of the skull. The mouth is very large and 
the throat extremely small. The nostrils are represented by a 
single or double blow-hole far back on the snout, nearly on top 
of the head. " When the whale breathes the expired air rushes 
out through the nostrils. The vapor in this expired breath, 
1 Beddard, p. 173. 



MAMMALIA 



327 



together with mucus from the nostrils, is condensed into drops of 
water m the cold regions, but the water taken into the mouth 
does not pass out through the blow-hole. The nose is directly 
connected with the windpipe, so that a whale can breathe while 
swimming through the water with its mouth open The eyes 
are relatively very small, and there are usually no external ears " 
(i races of external ears m the porpoise are recorded by Professor 
Howell.) The opening of the ear is minute. The cervical 
vertebrae are very short and more or less fused. 

The skin is smooth and shiny, like coach leather, and a thick 
coating of fat immediately underlies the skin. The blubber or 
tat from whales yielded much profit from its oil until the modern 




•^?^' i.^^'';~^'^^l*^*'^ °^ ^ whalebone whale, and section of the mouth 
with whalebone: b, Blow-hole; a, upper arm; /a, forearm- hh^nlT^hl 
small remams of pelvic or hip-bone, thigh, and eg; r,7oof of the mlate' 
w, «;, plates of whalebone; /, whaleboL-fringe. ^(Holdek ''ZooCv" 
American Book Co., Publishers.) ^ooiogy, 

method of getting oil from deep oil wells, and the scarcity of 
whales has almost excluded the whale industry from the oil 
trade. The toothed whales feed upon fish and larger marine 
animals, while the whalebone whales feed upon minute Mollusca 
jelly-fish, and Crustacea. 

The toothless whales are those in which the teeth, present in 
the embryo only, are replaced in the adult by baleen or whale- 
bone (Fig. 267), a horny product of the epithelium of the mouth, 
which consists of a large number (from 330 to 370) of horny 
plates hanging down like curtains in pairs, one on each side of 
the mouth, nearly meeting each other in the middle, each pair 
immediately behind another. The lower edges of these horny 
1 Beddard, p. 346. 



328 BRANCH CHORDATA 

plates are " frayed out" and form a strainer, through which the 
water taken into the mouth trickles out, leaving the small 
animals from the water in the mouth. This baleen or whalebone 
is worth several dollars a pound, and from 800 pounds to several 
tons are derived from a single whale. One whale has been re- 
ported as furnishing $12,230 worth of whalebone, and oil valued 
at $3490. 

Whales vary from 6 to 60 or 80 feet in length, and some have 
been found 100 feet long. The voice of some species has been 
described as similar to the lowing of a cow, and others like the 
bellowing of a bull. The young whale is called a calf. 



The great Ror'qual whales may measure from 60 to 85 or even 100 feet. 
A species of whale, probably of genus Balcenop'tera, is described as having a 
mouth so wide that " divers men might have stood up in it, yet the throat 
so narrow as would not have admitted the least of fishes." The blue 
whale (Baloenop'tera sibbal'dii) is the giant of the rorquals. The Califor- 
nia gray whale is said to be a cunning, courageous enemy. 

The "right whales" are from 50 to 60 feet long, the head about one- 
fourth the length of the entire animal, and with no dorsal fins. The 
whalebone is valuable and the oil is of excellent quality and large quantity. 
In toothed whales, which have no whalebone, the orifice of the blow-hole is 
single. 

The sperm whales {Physeter'idce) have teeth in the lower jaw only. Phy- 
se'ter macroceph'alus) is from 55 to 80 feet long. The head is enormous, 
ending in a great blunt snout. The mouth is ventral and " it has been as- 
serted that the sperm whale turns over on its back to bite."^ The single 
blow-hole is not in the median line, but on one side. Inside of the great 
" square head " is a cavity lying above the skull, which during life is filled 
with oil or fluid fat, of which the spermaceti of commerce is the product.- 
This oil is also found in other whales. Ambergris, an expensive substance 
used in connection with perfumery (which is at first a greasy mass and then 
hardens), is a product from the intestinal canal of the sperm whale. This 
whale is tropical. The females are found in herds or schools. Their food 
is chiefly cuttle-fishes. The throat is said to be large enough^ to have 
swallowed Jonah. It has great strength, being able to throw itself entirely 
out of the water. 

Dolphins and porpoises have many teeth which are present in both upper 
and lower jaw. The size of these animals is small to medium. The Be- 
lu'ga, or " white whale," is a northern species. It has a distinct neck and 
free vertebrae. The young are blackish, growing white as they mature. 
This porpoise ascends rivers in search of food, which is preferably salmon. 
One (Delphin'idce elphineraptus) is fairly common in the Gulf of St. Law- 
rence.^ 

1 Beddard, p. 362. 

2 Ibid., p. 365. 

^ Shipley and McBride. 



MAMMALIA 329 

Distribution. — Cetacea are cosmopolitan, mostly marine. A 

few ascend rivers, some being exclusively river forms of South 
America and southeastern Asia. 

Use to Man. — A good qualit^^ of ivory is obtained from nor- 
whal's tusks (the left upper incisor which sometimes reaches a 
length of 8 to 10 feet). Whalebone, oil, and spermaceti have 
already been mentioned. 

Geologic Distribution. — The cetaceans are represented in the 
Eocene and Miocene of Europe, Egypt, and North America. 
Both whalebone whales and toothed forms have been found in 
the Pliocene deposits. The toothed whales are represented in 
the JMiocene, Pliocene, and Pleistocene of Europe, Xorth Amer- 
ica, New Zealand, and Austraha by the extinct heterodont family 
Squalodon'tidce. 

Order VI. Ungula'ta. — This is a large order of diverse forms. 
A large proportion of these forms are extinct, and existing forms 
are connected to some extent by fossil forms. ]Many of these 
animals are very large. They are chieflj' herbivorous. The 
molar teeth are adapted for grinding by having broad cro-«Tis, 
with tuberculated or ridged surfaces. Canines are absent or 
small, or, in a few cases, tusk-like in the upper jaw. Although 
the older t^-pes were plantigrade, the existing forms, excepting 
such as Hyrax, are digitigrade, walking on the tips of their 
toes. The one-four terminal phalanges are nearly always en- 
cased in solid horny hoofs, which are, in reality, enlarged and 
thickened claws. The weight of the body usually rests upon 
these hoofs. The limbs have no power of grasping or climbing, 
but are simply organs of locomotion. Clavicles are absent. 
This is the only order of mammals in which horns appear. Thej' 
are surely a needed and effective means of defense in those forms 
which are too heavy to be swift, as they cannot defend themselves 
with teeth nor claws, as do the rodents and carnivores. The 
order contains many domesticated animals indispensable to man 
as beasts of burden or as food. It is the most beneficial to man 
of any order of mammals. 

The Hyrax (Hyrac'idce). — This and the following family are often 
placed in a sub-order. They are the survivors of those great animals of 
the past that had their wrist-bones placed in a longitudinal series and had 
toes which were nearly equal in length. The hjTax (Fig. 268) is a small 



330 



BRANCH CHORDATA 



animal found in Ethiopia, Africa, and Arabia, including Palestine.^ It 
is sometimes called the "rock-rabbit," since the most species live among 
rocks and mountains, and their squatty attitude, short tail, and split 
muffle, as well as a pair of rodent-like incisors in the upper jaw, remind one 
of the rabbit. They have no canine teeth. Some species are found upon 
the trunks and large branches of trees, and sleep in the hollows of trees. 
The skull shows affinity with the Perissodactyles and also with the rodents. 
The ears are short and the body fur covered. The clavicle is absent, the 
radius and ulna complete, but often ankylosed. The hyrax has a greater 
number of trunk vertebrae than any other mammal, twenty-one or twenty- 
two of them bearing ribs. The hyrax differs from all other mammals in 
having, in addition to the ordinary cecum, a pair of supplementary ceca 
situated some distance down the large intestine. 

The Elephant {Elephan'tidcE). — The skin is greatly thickened and scantily 
covered with hair. There is a tuft of hair on the end of the tail. The mass- 
ive, stiff limbs are quite free from the body. The nose and upper lip^ are 
produced into a long, flexible, muscular, prehensile trunk or proboscis (Fig. 
269), at the end of which the nares are situated. There are five complete 
digits on both fore and hind limbs, and though they are bound together in 




Fig. 268. — Hyrax syriacus. 



the integument, each is encased in a separate hoof. The skull is very large, 
but the bones are rendered light by their numerous air cavities. The brain- 
case is small in comparison with the size of the skull, as the bones are 
enormously thickened. In some specimens the bony skull wall is greater 
in diameter than the cranial cavity, the frontal bones in older animals some- 
times reaching the thickness of one foot. In existing forms there is a 
single pair of upper incisors, which develop into long tusks of solid ivory. 
A single tusk sold in London in 1874 weighed 188 pounds. There is no 
trace of any canines. Molars are so large that there is never but a single 
functional one on each side of each jaw at a time. They are transversely 
ridged. Elephants are herbivorous. The stomach is simple and the cecum 



^ This is supposed to be the cony of the Bible, where it is spoken of as a 
"wise, though a feeble folk." It is said to be too wise to be caught 
in traps, at least, but the further reference that it " cheweth the cud, but 
divideth not the hoof" throws some doubt upon its identity. However, 
Bruce kept one jn captivity and found that it did chew the cud. (See 
Beddard, p. 234.) 

^Beddard'e "Mammalia." 



MAMMALIA 



331 



wide. The cerebral hemispheres are much convoluted, but the cerebellum 
has no convolutions. There are but two living species: one {El'ephas 
africanus) is found in the forests of tropical Africa, the other {E. indicus) 
is found in India, Ceylon, and the Malayan Islands. The African species 
has not the two rounded bosses which give the wise countenance to the 
Indian species, and its head slopes back more and the ears are much larger. 
It is digitigrade, though a thick pad of fat makes it appear plantigrade. 
It reaches the height of about 12 feet. " Jumbo " was 11 feet to the shoul- 
der and weighed 62 tons. There are tusks in both sexes, but in this species 
they are larger in the female. The tusks are used not only as a means of 
defense, but especially the right one is used also for grubbing roots for food. 
The Africa'nus is more active and savage than In'dicus, but it has been 
tamed. It is not used in Africa now save for food and ivory. It is 
long lived, maturing at forty and living one hundred and fifty or more 




Fig. 269. — Various uses of the trunk of the elephant: 1, Drinking; 2, 
pulling grass; 3, washing. (From Holder's " Elements of Zoology," 
American Book Co., Publishers.) 



years. Elephas indicus is invaluable as a beast of burden on account 
of its great strength, though not all are to be depended upon. One may 
be perfectly docile and obedient, and another furious, vicious, and un- 
manageable, but, stranger yet, they are sometimes exceedingly timid. 
Baker tells of one he was riding fairly bolting at the sight of a hare. The 
elephant rushes into the nearest jungles, when bolting, tearing through 
the underbrush, while the rider is swept off or torn by the thorns. Its 
obedience to the slightest sign of the Indian mahout shows that it has con- 
siderable intelligence. Baker asserts that the locality and time of ripening 
of particular kinds of fruit are remembered by it. The power of remember- 
ing and recognizing individuals is proved by their revenge of particular 
treatment of certain keepers. This group of ungulates appeared in the 
Miocene. 

The Mammoth is an extinct form which once was found about the north 
pole in Siberia, Europe, and America. It was covered with long, woolly fur. 



332 BRANCH CHORDATA 

Fossil remains of another extinct form, the Mastodon, are constantly being 
found in the gravel pits of Europe, Asia, and North America. Some species 
have tusks in both jaws and tuberculated molars like the pig. 

The remainder of this order is included in the two great divis- 
ions of Perissodac'tyla (odd toed) and Artiodac'tyla (even toed). 

Perissodactyla. — The odd-toed group has the molars and 
premolars of the same size and the middle toe predominantly 
developed. " The other toes in the three living families are 
reduced to different degrees." 

The tapirs {Tapir' idoe) are among the oldest mammals represented to-day, 
the family being as old as that of Equidoe, though the specialization of the 
toes has never advanced so far. The fore feet are four toed, and the hind 
feet three toed. The nose and the upper lip are lengthened into a short 
proboscis. 

An American species (Tap'inis terrestris) is a solitary, dull and gloomy, 
timid and defenseless animal, hiding away near the stream, in the marshy, 
tropical woods in the daytime, and feeding at night. When alarmed or 
pursued it always takes to the water for safety. The jaguar is its most 
formidable enemy. 

The Malayan forms haunt the most retired spots among the wooded 
hills, thus escaping its enemy, the tiger. 

The tapirs (genus Tap'irus) are now found only in South and Central 
America, the Malay Peninsula, Java, and Sumatra. They are small or 
moderate sized, ungainly creatures, covered with brownish-black hair. 
The young is spotted and striped with white, as is the rule among quad- 
rupeds of the forest.! j'jig tapir's quick senses enable it to slip away, 
which it can do with great rapidity, when disturbed. When at rest in the 
daytime a Malayan form " exactly resembles a grayish boulder, and as it 
often lives near the rocky streams of the hill jungles, it is not easily de- 
tected." Tapirs are browsers, seizing and drawing the succulent leaves and 
shoots into the mouth with the proboscis. " They are extremely fond of the 
leaves of the low-growing cocoa plant, and they often in one night destroy 
a cocoa field which has cost a poor Indian the hard labor of a year." 

South American tapirs are said to make interesting pets. They are 
kept in the National Zoological Park at Washington. In Costa Rica the 
tapir is much hunted, for its flesh is good, both fresh and salted, and its 
thick hide is made into twisted whips (rawhides). 

The primitive forms were distributed all over the world, "but as the later 
tertiary conditions changed from torrid to temperate outside the tropics, 
they became extinct everywhere save in the hot, moist climate under the 
equator, where they have continued to the present time." Although now 
structurally very different from the horse of to-day, they probably repre- 
sent something of the character of the ancestral horse. 

The rhinoceros (Rhinocerot'idce) is a relic of nature's early attempts to 
formulate the solid-hoofed type of quadruped. It is recognized in fossils 
toward the close of the Eocene in both Europe and North America, and the 

^ Ingersoll, p. 372. 



MAMMALIA 



333 



skeletons of those of the Miocene differ little from those of to-day. These 
once numerous and widely scattered animals are represented by two 
African and three East Indian species. 

They have three short toes on each foot, each toe encased in a hoof-like 
nail. The central or third toe is the largest, but the weight is sustained by 
a sole pad. The East Indian forms (Fig. 270) have but one nose horn. The 
small Sumatran form and the African forms have two horns. These horns 
are simply outgrowths of the skin based upon a thickening of the nasal bone, 
and are composed of a number of tapering whalebone-like fibers, which 
sprout from papillae. They are finely cemented together, growing at the 
base as fast as they wear away at the tips. The usually naked skin is very 
thick, deposited in folds, making it look like plates of armor. In fact, the 
dried skin is used as shields by the oriental soldiers. The rhinoceros feeds 
upon leaves, twigs, and grass. It occasionally fights a tiger or leopard. 
It wallows in the mud. There is but a single calf at birth. The young are 
easily tamed. Selous says the white rhinocerous puts her nose close to the 




Fig. 270. — Indian rhinoceros {R. indicus) . 



ground and guides the little one (which precedes her) by keeping the point 
of her horn close against the rump. In disposition he says they are slug- 
gish, inoffensive animals, lying asleep in daytime, and coming to the water 
to drink in the evening. The African species are bluish graj^ when clean.' 

The long-lipped species of Africa {Rhino' ceros hicor'nis) has an over- 
hanging extensible upper lip with which it grasps and tears off the leaves 
and twigs upon which it feeds exclusively. The calf follows alongside of its 
mother. So sharp is the horn of a rhinocerous and so strong the head and 
neck that it can " disembowel and toss over its back any smaller animal, 
and it could rip open an elephant if it got at his side, though some African 
explorers say that the rhinocerous usually runs from a man ; but some are 
vicious." 

The horns are used as knife-handles and as weapons. The horn of the 
white rhinocerous {R. simus) has been known to measure 56 inches long, 
while that of R. bicornis is not known to exceed 40 inches. The Chinese 

1 IngersoU, p. 382. 



334 BRANCH CHORDATA 

and Burmese " pay high prices for the horns, tongues, and other efficacious 
parts of the eastern rhinocerous, to be ground into medicinal powders. "^ 

The horse (Eq'uidoe) has the most complete geologic record of any living 
animal. Fossil remains were found in the Eocene Epoch, on which there 
were four front toes and three hind ones. Then in the Miocene were found 
ancestors having three toes both before and behind, while at present this 
family is distinguished by a single functional toe on each foot, the second 
and fourth toes forming splint bones on either side of the toe. The tibia 
also is vestigial. 

In the Eocene times Europe and Asia were joined in the arctic latitudes 
by way of North America. The horse inhabited all continents except 
Australia, but it disappeared entirely from America in the later geologic 
ages, for which no adequate explanation has been made.^ At first it 
was adapted to a forest life, but it has come to be more and rnore adapted 
to living upon the high, dry plains, and it is one of the most highly special- 
ized animals in its adaptation to its environment. The remains of man 
and the horse are first found together in the interglacial or postglacial 
period. "There is abundant proof that men first hunted and ate, then 
drove, and finally rode the horse." 

The horse industry stands second only to the cattle industry among 
stock men. Horsehide leather is used for razor straps, gloves, and shoe 
uppers. The hair is used for upholstery and the bones for fertilizing, and 
the flesh for cheap meat. The mare's milk is used by the nomadic peoples 
of inner Asia. Koumiss, often used as a beverage, is fermented mare's 
milk. 

All our breeds of horses have been introduced from the Old World, as 
there have been no native wild horses in America. The ass, the zebra, and 
the recently extinct African quagga are also members of this family. 
The ass is wild in both Asia and Africa, and the zebra in Africa. The breed- 
ing of the hybrid mule is confined chiefly to the southern and some of the 
western states. 

Artiodactyla. — The even-toed ungulates, in which the third 
and fourth digits form a symmetric pair, have the three or four 
premolars smaller than the molars, and have a complicated 
stomach. 

The non-ruminants comprise the hippopotamus, hog, and 
peccary. They are omnivorous. The canine teeth are fre- 
quently developed into tusks. 

The hippopot'amus ( Hippopotarn'idce) is at present confined to Africa. 
It formerly inhabited Europe and there were also Indian species in the lower 
Pliocene. The common hippopotamus (Fig. 271) is thick skinned and al- 
most hairless. The two strong incisors on each side of each jaw and the 
canine teeth continue growing throughout life. The stomach is divided 
into two parts. The cecum is lacking. This huge animal, 14 feet long, has 
very short limbs and tail. The feet have four-hoofed toes. The hippo- 
potamus is nocturnal and aquatic, and not only walks rapidly along the 

1 Ingersoll, p. 378. 

2 Ibid., pp. 354-360. 



MAMMALIA 



335 



bottom of the river, but swims. It is thought that it swam from the Con- 
tinent across to Madagascar, thus populating that island with the genus, 
fossils of which are found in the swamps. The gap of the mouth is wide and 
the large teeth are used in cutting the bark from trees, which is a prominent 
feature of the food. They produce a strange carmine-colored secretion, 
"sweat," containing small crystals and corpuscles, from the skin. "Like 
other aquatic animals the nostrils are on the surface of the head and can be 
closed when under water," where it can remain not over ten minutes, and, 
after reaching the surface again, it spouts like a whale. It is a dangerous 
animal to meet, as it cannot only capsize a boat, but even bite out large 
portions of it and will attack man. 




Fig. 271. — Hippopotamus and young. (Holder's "Zoology," American 
Book Co., Publishers.) 



The hog {Suidoe) (Fig. 272) has four toes, but only two touch the ground, 
except in miry places. The nostril is situated at the end of the tough, 
proboscis-like snout. Hogs are generally covered with coarse hair or bristles. 
The stomach is simple and the cecum present. The typical genus Sus is 
found in Europe, northern Africa, Asia, and in the Malay Archipelago. 
The wild boar is Sus scrofa of Europe. 

The wild hog loves to wallow in the wet ground, but sees to it that 
"cover is handy." The male is usually solitary, while the female and young 
go about in groups of about a dozen. In India it makes huts of leaves, 
grass, and twigs, so interwoven as to be practically rainproof, in which the 
young are housed for several weeks. The domestic pig has been developed 
from the wild hog by artificial selection and intercrossing. The African 
wart-hog, the ugliest of land animals, and Bahiru'sa are allied. 

The hog industry in the United States represents hundreds of millions 
of dollars. One-third of the hogs of the world are produced here. Be- 
sides the pork used at home, large quantities are exported to Europe. It 



336 



BRANCH CHORDATA 



is said that at the large packing-houses everything about the hog is used, 
except the squeals. The hair is sold for mixing mortar or for making brushes. 
The skin is used for making foot-balls. The bones and teeth are carbonized 
and sold to sugar refiners or ground into a fertilizer. The sinews and hoofs 
are used in making glue, the intestines for sausage-casings, and the blood for 
making buttons, or, together with the refuse, for making fertilizer. 

American Hogs. — The collared peccary is our best representative of the 
wild hog. It is grayish black, with a white collar or streak about the withers. 
It ranges from the Rio Grande in Texas southward to Patagonia. It 
prefers moist, bushy, upland jungles, but it has been found in regions sur- 
prisingly dry, hot, and bare of vegetation. Peccaries go in small droves, 



Fig. 272. 




-Wild boar contrasted with a modern domesticated pi§ 
manes.) 



and feed at night on roots, mushrooms, farm products, and small animals. 
"When pursued, they run in open ground with great fleetness, and in cover 
will squat and dodge like a jack-rabbit." When cornered they are cour- 
ageous and pugnacious, fighting viciously, so that the boldest hunter "does 
not hesitate to climb the best tree that happens to be available." Only 
their courage and the use of their tusks have protected them from annihila- 
tion in forests infested with jaguars, pumas, wolves, and ocelots. If the 
musk gland is cut out as soon as the animal is killed the flesh is palatable. 



The ruminants, or cud-chewers, include the giraffe, deer, ox, 
sheep, and antelope. Teeth and stomach are both adapted to an 



MAMMALIA 



337 



herbivorous diet. In the upper jaw the canines are usually 
degenerate. There are generally no incisors, never more than 
a single pair, and in their place is a thickened calloused pad. 
The canines of the lower jaw have taken the form of incisors. 
The molars are selenodont, with crescent-shaped cusps; the 
stomach is usually divided into four compartments (Fig. 273), 
the rumen or paunch, which receives the food when it is eaten; 
from here it is regurgitated and chewed again as cud. It is 
then passed into the second division of the stomach, the reticulum, 
from which it passes into the third division, the omasum; and 
from there to the true stomach or abomasum. These animals 




Fig. 273. — Stomach of a ruminant (sheep), showing the four compart- 
ments: a, Esophagus; b, paunch; c, honeycomb or reticulum; d, liber 
psalterium or manyplies; e, true digestive stomach; /, beginning of the in- 
testine. (After Owen.) 

are usually large and many of them bear horns, which are larger 
(or exclusively) on the males. 



The Chev'rotain belongs to the primitive Asiatic and African family 
Tragu'lidcB. It is the smallest ungulate living to-day. It has both deer- 
like and pig-like characteristics. It is hornless a,nd the stomach has but 
three divisions. 

The camels and llamas (Camel'idce) have long limbs, with no trace of 
second and fifth toes. The rumen has smooth walls, and from it are devel- 
oped the water cells (Fig. 274). Camels are wonderfully adapted to their 
desert home by the sole pads on their feet; by their sandy color; by their 
long necks, which give long range of vision and enable them to reach the 
desert shrubs on each s'ide of their path; by their cartilaginous mouth, which 
enables them to eat the hard and thorny plants of the deserts on which no 
other animal could subsist; by their small ears; by the valve-like folds by 
22 



338 



BRANCH CHORDATA 



which the large nostrils may be closed against the simoons of the desert; 
and by their prominent eyes and heavy, overhanging eyelids. The hump 
is a real and acknowledged reservoir of nutriment stored up during moist 
seasons, as well as nature's pack saddle for the commerce of the ages.^ 
For centuries the camel has been the means of transportation over the desert. 
Papyrus records show it was well known in Egypt at least thirty-two 
centuries ago. Yet in all these centuries "little of sympathetic association 
has been gained between beast and master." Owing to its viciousness and 
stupidity it has been subjugated rather than domesticated. However, it 
has been developed into many serviceable forms, some swift and elegant, 
others strong and ugly. 

There are two distinct species of camels, the Bactrian or two-humped 
camel {Came'lus bactrianus) and the one-humped species (C. dromedarius) 
(Fig. 275). The two species will interbreed it is said, and it is not probable 
that either is now found in a genuinely wild state. The camel is a thickly 
built, ungainly pack horse. The dromedary is the finer-haired, light-step- 







Fig. 274. — a, Water-cells in the paunch of the camel; &, foot, showing 
the pad. (From Holder's "Elements of Zoology," American Book Co., 
Publishers.) 



ping race horse. The former travels three miles in an hour and six hours 
in a day, while the latter can run seventy miles a day. The latter is several 
times the value of the former. The single calf is weaned when about a year 
old, but it is not fitted for service until five years old. We are accustomed to 
think of camels as associated with heated countries alone, but the Bactrian 
camel can endure much cold, and carry on the overland trade between China 
and Russia across the plains of Mongolia or Turkestan amid the snows of 
winter and the dust of summer. Every spring the camel loses every frag- 
ment of its hair and for about twenty days it is as naked as if clean shaven, 
and is then sensitive to cold and rain. When the hair, which is at first fine 
and beautiful, becomes long and thick it can brave the severest frost. Its 
strong, elastic, lustrous hair is woven into warm cloth. The Andean vicu- 
nia has finer, soft, curly wool. The Arabian depends upon the camel for 
many things: "fuel, milk, hair for tents, ropes, shawls, and coarser fabrics; 
and flesh, leather, and bones from the dead animal. Camel's milk, though 

1 Ingersoll, p. 337. 



MAMMALIA 



339 



bitter from the wormwood pasturage, is the staple diet of thousands in 
Africa."! 

The genus Llama includes the llama, alpaca, huanaco, and vicunia. 
They differ from the camel in their smaller size and the absence of the hump. 

The llama was used in Peru as a beast of burden for centuries before the 
Spanish Conquest, and is still the only trustworthy carrier in the higher 
Andes. Its flesh is coarse and unpalatable, and its hair is coarser and in- 
ferior to that of the alpaca. It defends itself by "spitting," that is, forcibly 
ejecting not only the saliva, but the contents of the stomach at any offender. 
The discharge is injurious to man's eyes. The llama can also kick and 
bite. The alpaca is a smaller variety, bred in Peru and Chile for its thick 
growth of black to gray or yellowish woolly hair. "The Camel-tribe orig- 
inated in North America. It is represented by the Llamas of South 
America." — Scott. 




Fig. 275. — One-humped camel {Game'lus dromeda'rius). (Linnaeus.) 



The deer family (Cer'vidoe) is distinguished from all other ruminants by the 
presence of true bony antlers in the male; thf European reindeer and the 
American caribou have antlers in both sexes. These antlers may be little 
or much branched. They are never fused with the skull and are usually 
shed annually. Each year the new ones are larger and provided with one 
more tine._ It takes the antlers from ten to sixteen weeks to grow to matur- 
ity. During the greater portion of this time the males are weak and inof- 
fensive. At this time the does are rearing the young (fawns). When the 
new antlers are fully developed (about October) (Fig. 276) the males are 
as savage as tigers. 

The white-tailed Virginia deer {Odocoi'leus virginia'nus) is our most 
widely distributed deer. It weighs about 250 pounds, is light brown in 
summer and reddish brown in winter, with the under parts of throat and tail 
pure white. It crouches and carries its head low, and saves itself by clinging 

! Zwemer. 



340 BRANCH CHORDATA 

to the cover of brush or timber, in which it is not easily perceived until it 
starts to run, when it raises its tail and waves its "white flag" right and left 
in utter defiance of the rifle. If this white tail is not used as a recognition^ 
mark, it is surely unexplainable. 

The American elk or wapiti {Cer'vus canaden'sis) is the largest of the 
round-horned deer, handsome and tall as a horse, with a luxuriant mane 
and imposing antlers. The wild elks are nearly exterminated except 
in YeUowstone Park, though formerly abounding from the Adirondacks and 
southern Alleghenies to California and even Alaska. An effort is being 
made to restock the Adirondacks, but reckless hunters make it almost im- 
possible. The elk is both a browsing and a grazing animal. In winter 
those in Yellowstone Park migrate southward to the sheltering valleys of 
Jackson Hole. In summer they love to ascend the high mountains. They 




Fig. 276.—" Pushing match." (From life.) 

are kept in many city parks, as they breed freely in captivity. The red 
deer of Europe is a close ally. 

The reindeer (Ran'gifer taran'dus) of arctic Europe is unique in that both 
sexes bear horns. These are used not only for defense, but to shovel snow 
in search for food. Their fur is of a lighter color in winter. In Spitzbergen 
they migrate "in the summer to the inland region of the island, and in the 
autumn back again to the seacoast to browse upon the seaweed. "^ Rein- 
deer are annually imported into Alaska from Siberia for food and burden 
bearers for the natives. The multiplication of these reindeer has proved a 
source of food supply. The young develop into larger and stronger animals 
than their parents. 

Verj^ closely allied is the American caribou, which ranges from the east 
coast of Greenland to the west coast of Alaska. Next to the musk-ox it is 

^ Glossary. 

2 Beddard, p. 299. 



MAMMALIA 



341 



the most northerly of the ungulates. The caribou is an odd-looking animal, 
with thick long legs and with hoofs so expanded and flattened as to make 
good snow-shoes. Its covering is warm and consists of a "coat of fine wool- 
like hair, through which grows the coarse hair of the rain coat." It feels 
like a thick felt mat. The food is moss and hchen. These animals migrate 
southward in great herds, though they are not known beyond the Churchill 
River. In spring they return to the most northern headlands, where they 
bear their young. Upon these migrations the savages who live in these 




Fig. 277.— Rocky Mountain elk. (Farmer's Bulletin No. 330, U. S. Dept. 

of Agriculture.) 



arctic deserts of rock and snow depend for subsistence. Every part of the 
animal is used. The flesh, stomach, and intestines are eaten, as are the 
pomts of the antlers when soft, and the marrow of the leg bones. Soup is 
made from the blood and meat mixed together. The hair forms the warmest 
clothing; also tents cords, and shoe-strings. Knives and needles are made 
iromthe bones; hsh-hooks, spears, and knife-handles from the horns; while 
certain tendons serve as fine strong sewing thread for use with the bone 
needles. 1 

1 Ingersoll, p. 323. 



342 



BRANCH CHORDATA 



The American moose {Al'ces america'nus) is the largest member of the 
family (Fig. 278), living or extinct, and the male has the heaviest and widest 
spreading antlers.^ These are much flattened and expanded. The moose 
has a long, thick, and rather prehensile upper lip, and browses upon the 
bark, leaves, and twigs of certain trees, and upon moss and lichens. It is 
as fond of wading and swimming as a schoolboy. It is very fleet, and can 
pass over large fallen tree trunks or a 5-foot fence with ease. Its cry is a 
long, resonant bawl. The calf is not spotted. The male has a long, orna- 
mental strip of hair-covered skin, "the bell," which in the adult is sometimes 
a foot long. The cow has neither antlers nor bell. The moose is easily 




Fig. 278. — The Alaska moose {Alces americanus gigas). (Yearbook, U. S. 
Dept. of Agriculture, 1907.) 



handled and may be trained to drive in harness, but it does not live long in 
captivity except in forest preserves. During the stormy winter "they herd 
together in sheltered spots in the forest, and, through moving about in a 
small area, the snow is trodden down until they form a moose-yard" of 
several miles in extent. The animals browse upon the twigs of adjacent 
trees and bushes, and with their antlers keep their enemies, the wolves, at 
bay. 

The so-called "musk-deer" differs from other Cervidce in the absence of 
horns and in the presence of a gall-bladder, tusks, and the musk gland of the 

^ A pair of antlers from Alaska in the Field Columbian Museum has a 
spread of 78^ inches, and, together with the skull, weighs 93j pounds. 



MAMMALIA 



343 



male These glands, or "pads," as they are commercially called, form the 
basis for many manufactured perfumes, and command a high price, hence 
these deer are rapidly diminishing in numbers. 

■ "^^f^f furnishing fine venison and the many other articles already men- 
tioned, the deer family supplies "hartshorn," or ammonia. It is made from 




Fig. 279.— Giraffes feeding. (From Jordan and Kellogg's "Animal Life," 
D. Appleton and Co., Publishers.) 

the shavings and refuse left from antlers in the manufacture of handles for 
cutlery. 

The giraffes (Giraf'fida;) have many deer-like characteristics, but neither 
sex bears antlers. In their stead they have horny projections covered with 
hairy skin. The giraffe is the tallest of all animals, the top of its head being 
18 or 19 feet from the ground. Its neck, though so long, contains only the 
same number of vertebrae (seven) as that of man. Each vertebra is length- 



344 



BRANCH CHORDATA 



ened, still the neck is not long enough to reach the ground, so that in 
drinking or in reaching a tuft of grass the animal has to straddle out his legs 
and lower his position (Fig. 279). The giraffe's eyes are large, dark, and 
liquid, and its face has a gentle expression, but it is sometimes vicious and 
fights by kicking either with fore or hind feet. It has chocolate-colored 
spots separated by pale tawny markings or spaces, but these vary in both 
pattern and shade, proving a source of protective resemblance in the lights 
and shadows of the leafy trees, while the long neck may be mistaken for a 
weather-beaten tree-trunk. The under parts, shins, and feet are whitish. 
The long neck is useful in reaching the twigs of the trees upon which the 
giraffe browses, and also in allojving a wide range of vision , that it may look 
out for lions and leopards in which the long grass abounds. In locomotion 




Fig. 280. — Head of young prong-horn antelope. (After Hays.) 

the giraffe moves both the fore and hind limb of each side simultaneously, 
giving it a rocking motion. Giraffes are natives of Africa, there being a 
northern and a southern form. 

The North American prong-horn (Antiloca'pra america'na) (Fig. 280) 
seems to occupy, like the giraffe, an intermediate stage between the deer 
and the true antelope on account of the structure of its horns. The horns 
are branched in the male, like those of the deer, though having but two or 
three prongs. The horns of the female are not branched. These horns — 
that is, the external portion, corresponding to the "velvet" of the deer, but 
which is here a true horn — are shed annually. The prong-horn has no 
"false hoofs." The male is "about 38 inches high and of a varying yellowish 
brown above, darker on the face, dull white on chin and cheeks, in two 



MAMMALIA 345 

crescent patches across the throat, on the under surfaces, and in a broad 
heart-shaped patch around the brown scut of a tail." This whiteness of 
stern belongs in a greater or less degree to nearly all the ruminants and to 
other gregarious animals. It is thought to be a recognition mark by which 
the young and other members of a herd follow the leader or one another. 
The prong-horns are gregarious. The prong-horn is, or used to be, a crea- 
ture of the plains, living on the dry bush grass, and avoiding these wolf- and 
wildcat-inhabited thickets, but now frequently seeks their cover. The 
young fawns (usually two) cling close upon the heels of the mother, which 
defends them with lowered horns and sharp, striking feet. The fur is use- 
less, but the flesh is delicious. 

The cattle family (Bo'vidce) contains the wild cattle, the bison or buffalo, 
sheep, goats, and antelopes. They are distinguished by divided hoofs and 
unbranched horns, which consist of a hollow sheath growing over a horny 
core, which are never shed. As a rule they are present in both sexes. 
They have no upper canine teeth. They are heribvorous, preferring grass 
and herbage. Only a few examples can be mentioned here. 

The antelopes, so far as we know, are the oldest of all bovine animals. 
They date frorn the Miocene. They differ from true cattle in their more 
graceful form, in that the horns, when curved, curve backward toward 
the neck. Their skin is usually smooth and sleek. They are now limited 
to Europe, Asia, and Africa, predominating in tropical Africa. The 
sable antelope {Hippot'ragus nl'ger), says Gumming, "is the rarest and most 
beautiful animal in A.frica. It is large and strong, looking much like the 
ibex. Its back and sides are glossy black and the under parts pure white. 
The horns are upward of 3 feet in length and bend strongly back with a bold 
sweep, reaching nearly to the haunclres." The mane is erect, the hide satin- 
like, and the whole attitude fearless and noble. Like all the antelopes, it 
has an equine form and gait. It is readily tamed and seems able to breed 
in captivity. These antelopes love to pasture on the open plain, a few to- 
gether, mostly chestnut cows, says Ingersoll, and "the horns are used with 
undaunted courage even when attacked by lions." 

We cannot refrain from mentioning the small, active, beautiful gazelle. 
"The skin is as sleek as satin, of a color difficult to describe, as it varies 
between the lightest mauve and yellowish brown," the belly and legs from 
the knee down are white, the hoof tapers to a sharp point. "The head of 
the buck is ornamented by gracefully curved, annulated horns, perfectlji 
black, and generally from 9 to 12 inches long on the bend. The eye is the 
TTell-known perfection, the full, large, soft, and jet-black eye of the gazelle." 
The Dorcas gazelles are found in twos and threes all over Egypt. They feed 
upon juicy plants and shrubs, and visit the crops at night. They may stand 
motionless until the hunter is within rifle shot and then fairly skim the groud 
in their flight. 

Associated with the antelopes are the ugly gnus of South Africa. 

Sheep and goats are very closely allied, the goats differing from the 
sheep in their slight build, in the beard of the male, and in the horns, which 
are arched over the back instead of spirally curved, as is the rule with sheep. 

True goats (Ca'pra) are almost exclusively Palsearctic. They are repre- 
sented by the Spanish ibex (C. pyrenaica), the steinbock (C. ibex) of the 
Alps and Tyrol, and the Persian wild goat (C. cegagrus). The Persian wild 
goat is probably the principal species from which the tame goats are derived. 
According to Mr. Blanford, the "bezoar stones," the concretions of various 
lime salts found in the stomach, were supposed to be of great virtue as an 
antidote for poison. One stone of 4 ounces once sold in Europe for £200. 



346 



BRANCH CHORDATA 



Geologically, goats are traced back to the Pliocene. Their distribution is 
limited and varied, owing chiefly to their mountain-loving nature. Their 
different environments and tendency to vary have given rise to many and 
very various breeds of the domestic goat. 

The goats of central Asia, living in a climate of great extremes of tempera- 
ture, furnish the fine wool of Cashmere and Thibet, which is their under coat. 
The Angora goat of Asia Minor furnishes millions of pounds annually of 
long silky hair. The cashmeres and mohairs of our stores are from goat 
hair and wool. The leather from goat hide is always valuable, especially 
that of morocco, while the skin of the kid is valued for gloves. The goat 
has for many centuries been used as a domestic animal. It supplies an 
abundance of good milk, rich in cheese-making casein, and requires much 
less food than the cow. In southern Europe herds of goats are driven from 
house to house and milked at the door of each customer, and then driven 




Fig. 281. — Rocky Mountain goat (Haploc'eros monta'nus). 



back to pasture. The goat readily cleaves to the household and exhibits 
more intelligence than other members of our flocks and herds. 

The chamois of the European Alps and the Rocky Mountain goat (Fig. 
281) are described as goat antelopes. The Rocky Mountain goat is the 
nearest we have to the goat, for this is not a true goat nor a true antelope. 
It is twice as large as a goat and looks much like a miniature buffalo, only 
its pelage is pure white, soft, and fine. Its hoofs, horns, and nose are black. 
"It has high shoulders, low hind-quarters, thick legs, and neck. It carries 
its head low. Its face is long." The small, angular hoofs consist of a 
pad inside and a knife-edge outside, equally adapted to snow or bare 
rock. It "inhabits the grassy belt of high mountains just above timber line, 
and loves the dangerous ice-covered slopes," being able to ascend almost 
perpendicular precipices. It is exceedingly difficult to capture and does not 
live long in captivity. "It is now found in only Idaho, Washington, and 



MAMMALIA 



347 



northwest Montana. It is scattered at long intervals through British 
Columbia and Alaska, as far as the head of Cook's inlet. "^ 

The sheep {Ovis) are almost entirely palaearctic and nearctic, barely 
getting into the oriental region. They, like the goats, are often limited to 
islands and small stretches of country, owing in part to their mountain- 




Fig. 282.- 



-The White Mountain sheep of Alaska {Ovis dalli). 
Yearbook, 1907, U. S. Dept. of Agriculture.) 



(Osgood, 



loving habits (Fig. 282). There are six North American species. The 
Rocky Mountain big-horn (Ovis montana) ranges from the far north to New 
Mexico. The mountain sheep is a fine, sturdy animal, bold, keen-eyed, 
active, and strong. It fears no storm and defies all enemies, save man with 
his gun and domestic sheep with their diseases. It delights in the highest 

1 Hornaday. 



348 BRANCH CHORDATA 

crags of the mountains, the boldest rim-rock of the plateau, or the most 
rugged "bad lands," for which it is adapted by its round firm hoofs, its 
warm winter under coat, its ability to subsist on scant herbage, and its keen 
senses. It is hunted by mountain lions and by man for its savory flesh. 
It has a handsome head and massive horns curved into the half or three- 
fourths of a circle, as are the horns of no other wild animal. It needs to be 
seen in its native cloudland to be fully appreciated. 

There are many breeds of the domestic sheep. The original of this per- 
haps most useful and least educated of animals is not known. The variation 
of external characters, such as horns, ears, and tail, and in the color, length, 
texture, and quality of the fleece, is exceedingly great. The existence of 
these numerous breeds is probably due to their tendency to vary and to 
effect fertile crosses, and to long-continued selection, combined with the 
obstinacy with which these variations are transmitted and retained. Sheep 
are used to an enormous extent both for the production of their wholesome 
flesh and for their wool. Thousands of Persian lamb skins are used in the 
fur trade annually, and hundreds of thousands of Astrakans, which is the 
same breed taken when exceedingly young, it is said, before their natural 
birth. This breed is also greatly valued for its fat, which accumulates on 
the haunches in two great protuberances. In the fat-tailed sheep of Asia 
the tail of pure fat sometimes weighs 30 to 50 pounds, and trails upon the 
ground if not suspended upon wheels or carried upon a truck. This fat 
is regarded as a great luxury. The Spanish Merino sheep has been intro- 
duced into South Africa, Australia, and the United States. It is celebrated 
for the fine quality of its wool. 

The musk-ox {O'vibos moscha'tus) is a strange, long-haired, short-legged 
creature of the frozen North. It belongs between the sheep and ox, par- 
taking of the characters of each. 

Oxen are distinguished from other hollow-horned ruminants by their 
stouter build, and by their smooth curved (not twisted) horns, which stand 
out from the sides of the head. The wild ox of Europe {Bos 'primigenius), 
believed to be surviving in the herds of Chillingham and Chartley,i is 
supposed to be the progenitor of our cattle. The original, called the auroch, 
or, by the Romans, Urus, was of more gigantic size. 

One of the largest of the family to-day is the European bison {Bos 
bonasus). It looks much like our American bison or buffalo, but is taller. 
Bisons differ from oxen in having a hump over the shoulder formed by 
spinous processes for the attachment of the great muscles used in holding 
up the massive head and in the great pushing matches of the bulls. The 
American "buffalo" is more shaggy and robust than the European "wisent " 
(Fig. 283). The latter was forest inhabiting, while our "buffaloes" loved 
the plains, where they congregated formerly in great herds in spring and fall, 
but usually formed only scattered bands which traveled over the plains in 
single file. The true buffalo of Africa and India has no hump and is almost 
hairless. No animal is more dangerous than an infuriated bull buffalo, and 
none more easily provoked. Pugnacity and revenge are its ruling impulses. 
It has been domesticated in India, and is very useful, but not lovable. 
Africa has two species, which are sometimes accompanied by starlings. 
In the East starlings and herons "perch on their backs and hunt for ticks 
and other parasites" — a strange, but mutually beneficial commensalism. 

The yak {Bos grunniens), of the mountains of Thibet, has short legs, 
goat-like feet, humped shoulders, smooth, spreading horns, and carries its 

1 Beddard, p. 321. 



MAMMALIA 



349 



head low. From the chin, throat, and lower parts of the sides the hair 
grows long and forms a fringe, a wonderful adaptation to the climate. This 
long hair serves as a mat beneath it when it lies down upon the ice and snow, 
as well as a warm cover under which it curls its legs. The tail is thick and 
silky, sometimes 6 feet long. It is often beautifully mounted on antelope- 
horn handles and used for fly- whisks in the East. The cry is much like the 
grunt of a pig, but louder and longer. ^ Tame yaks have long been used as 
strong, sure-footed beasts of burden. The flesh, milk, and butter are ex- 
cellent. From its hide, clothing, tent covers, and harness are made, and the 
hair is twisted into ropes. 




Fig. 283. — A group of buffaloes, " American bison " (Bos americanus) in 
Yellowstone National Park. (From life.) 

The numerous breeds of domestic cattle form an enormous industry. 
The exports of the United States alone, such as cheese, butter, hides, tallow, 
and beef, amount to many million dollars annually. 



Geologic Distribution of Ungulates. — The camel is represented 
in the Ohgocene. The Miocene forms in America had horns 
something hke deer antlers. ■ The Procamelus, the probable 
ancestor of both camels and llamas, flourished in the Miocene. 
In the Pliocene, Europe had deer, antelopes, oxen, and the first 
1 Ingersoll, p. 247. 



350 BRANCH CHORDATA 

Old World camels, as well as giraffe-like forms. " That the 
camel got the pads on his feet, the water-pockets in his stomach, 
and the other drought and sand resisting arrangements from an 
ancestor that began in the United States a million or more years 
years ago " has been proved by Cope, Doctor Wirtman, and his 
assistants. The oldest fossil deer types are Miocene. They 
were small, hornless creatures. The first horned deer were in 
the middle Miocene, when the horns were bifid. The giraffe, 
or its close allies, existed in the Miocene. The bison existed in 
the Miocene, as shown in fossil Bos sivalensis from India. The 
Pliocene life included a variety of oxen and two North American 
bisons. 

Order VII. Rodentia or Gli'res. — Rodents are exceedingly 
numerous and well-known mammals, covered with fur or spines. 
They are generally small, varying in size from the porcupine, of 
about 3 feet in length, to some of our small mice, not over 4 or 5 
inches long. 

The one distinguishing characteristic of rodents is their teeth. 
(See Fig. 288, p. 355.) These have enamel on their front surfaces 
only. Thus, their incisors, which grow continuously from per- 
sistant pulps, are always chisel shaped and kept sharp by the 
wearing away of the posterior surfaces. There are never more 
than two incisor teeth in the lower jaw, and only two in the 
upper, except in Lepor'idce, where there are four. The lack of 
canine teeth in all rodents leaves a space or diastema between 
the incisors and the molars. The molars vary in number from 
two to six on each side of each jaw. There is a hairy ingrowth 
in the mouth back of the incisors, which serves to catch the 
particles when the animals are gnawing. They are usually 
vegetable feeders, but some are carnivorous or omnivorous. 
The intestine is long and the cecum large (except in dormice) and 
often complicated. 

As a rule the clavicle is present. Most rodents are five toed. 
The toes have claw-like nails. They are usually plantigrade or 
semiplantigrade. The cerebrum is small and nearly or quite 
smooth, but in some of the larger forms (the beaver excepted) 
it is well convoluted. The ears and eyes are well developed. 
The voice is a squeak or squeal. Their defense is by spines, 
as in the porcupine; by biting, as in the rat; and by flight or 



MAMMALIA 351 

concealment, as in the rabbit, though the rabbit will fight vi- 
ciously by biting and by striking with its hind feet if cornered, or 
if the nest or " form " containing the young is attacked. 

Some hibernate in winter, others migrate in flocks. They live 
almost everywhere, but are chiefly terrestrial; some are aquatic, 
some subterranean, and still others arboreal. They are very 




Fig. 284. — American flying squirrel {Sciurop'terus volucella) . (From Pack- 
ard's "Zoology," Henry Holt & Co., Publishers.) 

proliflc, the young being numerous, and, in some families, four to 
six litters a year. Since they are hardy, often nocturnal, and not 
very particular as to the character of their food or lodging, they 
have become worldwide in distribution. 

Squirrels {Sciu'ridce) are worldwide, excepting Australia and Madagascar. 
The eyes and ears are large, the tail long and bushy, the thumbs on the fore 
feet inconspicuous. There are four toes on the hind feet and the tibia and 



352 BRANCH CHORDATA 

fibula are distinct. They feed upon nuts and grain, as well as eggs and 
young birds. They are chiefly arboreal, building their nests in tree-tops. 
They lay up a store of food in hollow trees, where they pass the severe 
winter weather. Four species of this genus (Sciurus) are found in the 
United States and Canada. S. vulgaris, the common squirrel of Great 
Britain, is found from Ireland to Japan. 

Flying squirrels (genus Sciurop'terus) (Fig. 284) of the palsearctic region 
(which includes Europe, northern Asia and Japan, North America, and 
India) have a furrj' membrane connecting the anterior and posterior limbs. 
This, together with the broad tail, acts as a sort of parachute, enabling these 
squirrels to take enormous downward leaps from limb to limb or tree to 
tree. They cannot "fly" upward, but ascend the tree by climbing. The 
Asiatic flying squirrel is 16 to 18 inches long without the tail, and, it is said, 
80 yards have been covered in their longest leaps. 

The little striped ground squirrel (Tamias striatus) burrows and carries 
its food in its cheek pouches to its nest in the ground. 

The prairie-dog (genus Cy'nomys), of the great western plains, is also sub- 
terranean, digging a burrow and throwing up a mound at its entrance. 
There are whole villages of these mounds, sometimes covering acres. The 
prairie-dog hibernates in winter, at least comes out only occasionally. One 
kept in a cage by the author comes out of his "straw burrow" at night or 
just before dawn, only at long intervals, for food. They sit up on their 
hind feet and look all around like sentinels, but dart back into their burrows 
again at the least approach of danger, uttering a shrill cry as a warning to 
the rest of the community. They are so quick of movement that it is diffi- 
cult to shoot or trap them. Their ears are small. Their legs are so short 
that in running they "hug the ground," of which, in sandy regions, they are 
very nearly the color. They grasp their food with their paws like true 
squirrels. 

The marmots of the arctic regions are closely allied to these. The Alpine 
marmot {Arcto'mys marmotta) lives far up in the Alps. Its danger signal is 
a shrill whistle. These marmots hibernate, ten to fifteen being packed 
together in a well-lined burrow. 

The North American beaver (family Castor'idoe) is an aquatic rodent with 
a stout body, flat, scaly tail, and webbed hind feet. It fells trees by means 
of its strong incisors, damming the stream so as to raise the level of water 
above the entrance to its burrow. The beaver (Castor canadensis) is fast 
becoming exterminated on account of the demand for its fur. 

Rats and mice (Muridoe) have naked tails which are scaly underneath. 
The soles of the feet are naked and the tibia and fibula are united below. 
Some of the numerous genera are found in all parts of the world. The 
muskrat is the largest member of this family. Some of the species are 
among the smallest quadrupeds known. 

The North American muskrat (genus Fiber) is a genus of two species of 
dark brown aquatic animals. They dig burrows in the banks of streams, the 
entrances to which are beneath the surface of the water. The hind feet 
are slightly webbed, the tail flattened and scaly, with scattered hairs. 
The shortened thumb has a fully developed claw, and they grasp theii food, 
which consists of roots and water plants, with their paws, like the squirrels. 
A Rocky Mountain species (Fiber osoyoosensis) is said to construct a dome- 
shaped house of "bulrushes" in the water. It feeds largely upon water- 
fowls and fish. 

The common mouse (Mus mus'culus) and rat (M. decumanus) have 
been introduced into America from the Old World. M. minutus is said to 



MAMMALIA 



353 



be the smallest British quadruped, except the lesser shrews. It is 2^ inches 
long without the tail, which is the same length. The water rats or vdes 

mris^N'"'' T^'^^'^^'i ^^f. '^' ™^^^°^ "^^^'^ °^ "fi<^ld mice" {MicZusj 
^ fW-,??r- ^^^ *yP/c.^l ^eld mouse IS a "short-eared, short-tailed thick^ 
set httle creature 4* inches long, with a tail H inched long. I Ts brown 

nSr T?/''w°' ^'^^''^ ^'^r- I' '^ ^°^^d from the Atlantic to tie 
Dakot^s. It feeds on grass, roots, and grain. In severe winters they some- 
times do much damage by eating the bark of young trees (Fig 286) 

Dormice.— 1 he common dormouse of the Old World {Muscardi'nu's avel- 
lanartus) has a long bushy tail and looks much like a tiny squirrel Its 
body IS "3 inches long with a tail 2^ inches long " 




Fig. 285. 



-Carson field or meadow mouse (Microt'us montanus) . (Yearbook 
U. S. Dept. of Agriculture, 1908.) 



The American porcupines are chiefly arboreal. The quills, which are 
but an inch or two long and are somewhat hidden among the intermingled 
tevf "" T?^ attached sothat when an animal comes in contact with 
rp^^;n^7ff ' '"^° '*'t^"'^' bemg barbed, they pull out of the porcupine and 
^^ ^f II *h^,^"emy^ Hence porcupines are considered a nuisance by cattle- 
men of the West. They are also annoying to the lumbermen of the North, 
as they gnaw the wooden handles of their tools. These animals are so well 
protected by their spmes that they need little intelligence to escape their 
enemies and are rather stupid. The Old World porcupines, by some 
authorities placed in another family, have spines a foot in length. On the 
tail are hollow quills, which make a rattling noise somewhat like that of the 
rattlesnake to warnthe enemy. The South American genus has a prehensile 
tail. I fie httle guinea-pigs are South American relatives. 
23 



354 



BRANCH CHORDATA 



Jumping-mice (Dipod'idoe) (F^g. 287) are represented by the American 
jumping mice and the Patearctic Jerboas. They have long tails and the 
hind legs are greatly elongated and adapted for taking enormous leaps. 




Fig. 



286. — Lombardy poplar killed by field mice. (Farmer's Bulletin 
No. 335, U. S. Dept. of Agriculture, October, 1908.) 




Fig. 287. — Jumping mouse. (After Tenney.) 



The pouched gophers {Geomy'idce) have large cheek pouches opening ex- 
ternally (Fig. 288, a, b, c). These burrowing rodents are restricted to Cen- 
tral America and the central plains of North America. They have small ears 
and eyes. The claws of the anterior limbs are strong. 



MAMMALIA 



355 



The family Leporidce is represented by hares and rabbits. Formula for 
the teeth: Incisors, ^; molars, ^, or 28 in all. One pair of upper incisors 
is much smaller and immediately behind the other. This arrangement of 






C 



Fig. 288. — Faces of pocket gophers, showing pouches and incisors: 
a, Geomys; b, Cratogeomys; c, Thomomys. (Yearbook U. S. Dept. of Agri- 
culture, 1909.) 

the incisors has given rise to the term Dwplicidenta'ta. The soles are furred, 
the tail short and recurved, the eyes large, and the ears long. The hind limbs 
(Fig. 289) are longer than the fore limbs (Fig. 290), and they "run" by 




Fig. 289. — Posterior limb of Jack-rabbit. (Mounted by students.) 



prodigious leaps. Genus Lepus contains thirty or forty species. Our 
common forms in the United States are the "cotton-tail" (L. sylvalicus) ; 
the marsh hare (L. palustris); the water rabbit (L. aquaticus), also a south- 



356 BRANCH CHORDATA 

ern form; the Jack-rabbit (L. campestris) of the West and Southwest; and 
L. americanus, a northern variable species, whose fur turns white in winter. 
They are not gregarious, though it is said they often play together on moon- 
light nights. They are crepuscular and somewhat nocturnal. 

Geologic Distribution. — Rodents appeared first in America in 
the Wasatch stage of the Eocene. Ahnost all the principal 
groups of existing forms appeared within the tertiary.^ 

Use to Man. — Great numbers of rabbits are used for food in 
the cities during the winter season. Their fur is used for making 




Fig. 290. — Scapula and anterior limb of Jack-rabbit. (Mounted bjy 

students.) 

felt hats. " Nine-tenths of the felt hats worn in the United 
States are made from rabbit-fur." Where they are numerous 
or food is scarce they gnaw the bark of young fruit trees. In 
many localities the orchard is enclosed in rabbit-proof fence. 
Beaver skins are also much used for furs. 

Order VIII. Carniv'ora (" Mammals of Prey "). — These flesh- 
eating mammals may be small or large. They may be terres- 
trial, arboreal, or aquatic. They feed upon the flesh and blood 

^ Parker and Haswell, p. 574. 



MAMMALIA 357 

of other animals, which they catch by cunning, by chasing, 
or by stealthily creeping up and pouncing on them, where- 
upon they bite and tear them in pieces. Here we found an-' 
other striking illustration of the adaptation of structure to 
habits. They must be fitted to attack and destroy other ani- 
mals. Their five or four toes are armed with sharp claws, which, 
in the cat, are retractile into a sheath by which they are pro- 
tected when not in use. The teeth are adapted for seizing, 
biting, holding or cutting, in contrast to the nibbling or grind- 
ing teeth of the herbivores. The usually six incisor teeth are 
small. The canines are long, strong, and conical, fitted for 
tearing, and the premolar in the upper jaw and the first molar 
in the lower jaw, called the " carnassial teeth," are developed 
into thin, sharp, three-pointed fangs, shutting down past one 
another like scissor-blades, while the cusps of the molars form 
more or less angular and sharp ridges. 

The stomach is simple, and the cecum small or wanting. 
The clavicle is reduced, the radius and ulna well developed. 
As to manner of walking, there are several gradations from the 
plantigrade bears, which walk on the soles of their feet, to the 
digitigrade cats, which walk on the tips of their toes. The 
coloration is varied to conform to their habits. Some are 
spotted, others striped, while many adults are quite modest in 
their plain, uniform colors. The brain is large and well convo- 
luted, and the sense organs well developed, giving them a high 
degree of intelligence. 

This provision of nature, wherein some animals feed upon 
vegetable matter and others feed upon animals — for every living 
thing, from the microscopic algae in the water to large animals 
like the deer and horse, becomes food for some animal— is a 
wise one. For thus the vegetation of the earth supports not only 
the herbivorous animals feeding directly upon it, but the carniv- 
orous animal has his food very largely prepared for him by the 
vegetable-feeding animals. But the carnivorous animal also 
aids the herbivorous survivors in their struggle for existence, for, 
was not the number kept within bounds, the rapidly multiply- 
ing herbivores would soon absolutely destroy the vegetation of 
the world. 

These animals are usually clothed in dense^ soft hair, and 



358 BRANCH CHORDATA 

many of them are valuable for their fur. The cat and dog have 
been domesticated. 

The Terrestrial Carnivora (Fissipe' dia) . — The number of 
.digits may be five on each foot, but is often reduced to four on 
the hind feet, as in cats and dogs, and sometimes to four on the 
front feet, as in Hyce'nidce, but the reduced first toe may bear a 
claw. 

The cat family (Fe'lidoe) includes the lions, tigers, leopards or pan- 
thers, jaguars, pumas, lynxes, wildcats, etc. They are widely distributed 
in both the Old World and the New, but are absent in Australia. 
They seem to have evolved in the Old World first, migrating to North 
America at the close of the Pliocene, and from thence to South America. 
The legs are relatively short and the claws are retractile. The terminal 




Fig. 291. — Bones and ligaments of the toe of a cat, showing the claw re- 
tracted (A) and protruded {B). 

joint bearing the claw (Fig. 291) folds back into a sheath by the outside 
of or above the middle joint, and is held there by a strong Hgament. This 
is the natural position of the claw and prevents it from friction. When 
wanted for aggression or defense it is pulled into position by the flexor 
muscles bearing the claw. 

The raccoons {Procyon'idcB), placed by some with the bear family, are 
plantigrade and omnivorous, eating anything in the way of fish, oyster, 
crayfish, flesh or fowl, and green vegetables especially corn. They have 
the peculiar habit of washing their food. They are nocturnal. The limbs 
are long and the soles of the feet naked. "The raccoon is at home in the 
timbered regions of the southern and eastern United States where there are 
swamps," for it loves to play and to fish in the water. It has long active 
fingers, and uses its hands as cleverly as a monkey. It makes its home in 
the hollow limb of a tree. The annual family of five or six young follow the 
mother about for a year. In August the "coons" are fat and the flesh is 
tender and juicy, and "coon hunting" is a great sport. The young are easily 



MAMMALIA 359 

and the mother guards them so icitously. It takes seven vp«r« f^!.^ ^ 

rouTsYndv''''thefr^T '^^^' ^° -Pt-itr t\1 Tairb^a^s '^aTdS 
themselvel "' '°'^^'' ^'" accompanied by their cubs, often as bTg as 

exceedingly \ormidaile. It lanming'w:ws\'^^^^^ 

vSSfs t'deafh "Vf ^'"- " buffalo with'one blow"' Itdoynot'hSgTts 
victims to death. The grizzly flees from man unless cornered In ooS 

in a sorfT P'"' 1-'' ^"^^^ T ^"^^le to obtain food the^^^ass the wS 
ma sort of sleep, livmg upon their fat stored up in the fall but thevdonS 
become torpid as the cold-blooded animals do. In some spects S ma^^^ 
which hibernate singly, come out from time to time. SyTnot WbSSate 
of It tTi.'^ "°'i '" captivity, leading us to bdieve that the wbterSeeo 
of the north is only another adaptation to environment ^ 

or wTnf goth o?'l''^' '^^ P°^"^ b^^^u^'^-^^ "byTent rather than sight 
bears exc^ent the n^^^^^^^ '""^ ''Tu^? be somewhat dull." All American 
S Hghtesf in sn^^^^^ be^r, change their color being darkest in late summer 

bea^??J'rl^^L^n?«^'^n \w J"^ T^^'d ^^^ later in the New did the true 
uears 1, ursus) appear, feo this family, which is highly snecialized \r> qn^A 
features and very primitive in otherj i. among tfe Jo^nlSrof the S! 

t=.t£Sri,?,?^-^^^^^^^^^ 

The North American otter is still occasionally found "in Florida, Carolina, 
^ II Kings ii, 24. 



360 BRANCH CHORDATA 

Canadian provinces, in a few localities in the Rocky Mountain region, and 
from British Columbia to central Alaska." The home for the rearing of the 
two young is a burrow in the bank of a stream. The sea otter {Latax lutris) 
feeds largely on sea-urchins and shell-fish, and its molars are flattened and 
the tubercles very blunt, for crushing the shells. This animal has been so 
much hunted for its exceedingly valuable fur that it has changed its habit 
of feeding upon the shore to hunting in the deeper waters, and makes its 
bed on floating masses of kelp. It is rare except in Alaska, and is one of the 
wildest and wariest of animals. At present the otters are among the most 
valuable of all fur-bearing animals, a single skin of the sea otter having been 
sold in London for £250, or about $1250. 

The badger (Meles) has naked soles and the claws of the fore feet are 
much longer than those of the hind feet. The true badger of Europe and 
eastward is nocturnal, omnivorous, and burrowing, loving the woods. 
The South American badger resembles the European one, but is smaller. 
Its three or four young are born naked. Its body, which is about 2 feet 
long, is broad and flat, and its legs very short. It has a sullen, savage dis- 
position. It feeds on ground squirrels and prairie-dogs. It ranges over the 
Great Plains, the Rocky Mountains and westward, and from Mexico to 
Alaska. In the United States it is more or less active all winter, being able 
to find food, but farther north it is forced to spend the severest portion of 
the winter in semitorpidity. There are a number of species in Asia. The 
Teledu {Myd'aus nielictes), of Java and Sumatra, is said to rival the skunk in 
the odor of its secretion. 

The skunks (Mephi'tis), of which there are nine species, are widely dis- 
tributed in America. They are distinguished by their jet black color, 
variously banded, with longitudinal bands or spots of pure white, making 
them conspicuous. This is surely a fine example of warning colors, for both 
man and beasts are well aware of the strong offensive odor of the anal se- 
cretions which can be ejected for a distance of several feet. Despite this 
efficient means of defense the skunk is sometimes devoured by the puma, 
the harpy eagle, and the great horned owl. It is destructive of poultry, 
but is a destroyer of myriads of noxious insects and mice. The fur is ex- 
tensively used, first being dyed. 

The marten and weasel tribe is distinguished by a long slender body, 
short legs, and cat paws. These smafl, agile creatures have valuable 
fur. The group includes the Siberian sable, the North European marten, 
and the Canadian pine marten. The marten is 18 inches long, with a rather 
bushy tail of 7 or 8 inches. It is brown above, lighter below, and varies 
according to the age, sex, and season. "The winter fur is thick, soft. If 
inches deep, of the richest hue, and has scattered through it coarse, black 
hairs which the furrier pulls out." The six or eight young are born high up 
in a hollow tree or in a rocky crevice. The Canadian marten is not a poultry 
thief nor wanton murderer, but kills what it wants to eat of squirrels, hares, 
and grouse, trailing them with the nose to the ground like a hound. Few 
animals will eat the marten unless extremely hungry. 

The mink is small and of a chocolate or yellowish-brown color, with a 
round hairy tail. It is scattered throughout North America along the banks 
of streams. It feeds chiefly upon birds and is a "wanton murderer." The 
black-footed ferret is nearly always found in the prairie-dog villages. The 
English ferret is simply a domesticated variety of the polecat {Puto'rius 
fetidus) .^ 

1 Beddard, p. 436. 



MAMMALIA 361 

The weasel is the smallest animal of the group. The body is very long 
and ''no thicker than a man's thumb." Its fur changes from brown in 
summer to white in winter. This winter fur is known as ermine, and comes 
from Alaska, Canada, Lapland, Russia, and Siberia. It is used not only 
for ladies'" garments, but for the robes and crowns of kings. The smallest 
of all Carnivores is Putorius rixosus, of northwestern Canada. It is only 
6 inches in total length and brown to the tip of its tail. In all other species 
the end of the tail is black. The change of color to white helps to retain the 
bodj' heat, and helps also to conceal the animal from its enemies and its 
prey. Poulton believes that the cause of this change of color is the lower 
temperature acting upon the skin, and that existing dark hairs become white 
at the tips. Others maintain that in cold regions the summer pelage is re- 
placed in winter by hairs which come in wholly' white, while in warm regions 
the new winter coat is brown. However, Doctor Coues says he has seen 
many autumnal skins which were white at the roots and dark at the tips. 
In any case, natm-al selection has preserved those individuals having the 
power of changing the color of the fur imtil this character is now general. 

The dog family {Canidce) is universally distributed, with the exception 
of Xew Zealand. These animals have a simple, cjdindric cecum and usually 
five toes. Perhaps the most striking feature of the family is the bladder- 
like inflation of the auditory bulla, that part of the skull containing the 
internal ear. This apparatus and sense is perfected in the dogs. Many of 
this family are familiar. 

There are several genera, but the principal one is Cards, including our 
dogs, wolves, foxes, and jackals. Huxley divides them into fox-like and 
wolf -like dogs. The foxes are more active than the wolves, with a "broad 
skull, sharper muzzle, larger ears, a more bush}^ tail, and, usually, longer 
fur." Thej^ are notably clever and quick witted, and often show skill in 
meeting new situations made by the advent of man. 

The typical fox is the common red fox (Vulpes fulvus), of wide distri- 
bution. Our American form varies from the typical yello'n-ish red, darkest 
on the back and shoulders, to a very bright or very pale yellowish red. 
It may have the markings on the spine and withers very dark and distinct, 
making it a "cross-fox," or be totally black with a w'hite-tipped tail, or black 
with the tips of most of the hairs white, giving the fur a frosted or silver 
appearance. Either of the last two cases is called "silver fox." These rare 
and valuable variations may occur in the same litter with the normally 
reddish ones. Foxes feed upon ground birds and their eggs, rodents, frogs, 
lizards, insects, and fruits. The3" may be caught by rapid chase, by digging 
the burrowing forms out of the ground — for the fox is naturally a burrower — 
by stealthilj' creeping up on them, or by lying apparently dead until the vic- 
tim approaches, and then pouncing upon it . While it does sometimes raid the 
hen coops, the fox does good service in destro>Tng rats, mice, and gophers. 
It sometimes stores its surplus food. Its enemies are all the large cats and 
wolves, as well as man and dogs in the so-called sport of fox chasing. The 
red fox has a litter of seven or eight young; the southern gray fox, of four or 
five. The gray fox is smaller. It chmbs trees to get the ''sour grapes" and 
persimmons, but it cannot adapt itself to the prairies. The arctic fox 
(Vitlpes lagopus) furnishes another example of color variation under the 
influence of a different climate. In the extreme north it is snow white all 
the year round. A little farther south it is brown, with the under parts 
lighter in summer and white in winter, while in the southern part of its 
range, as in the Aleutian Island and parts of Greenland, it is most often bluish 



362 BRANCH CHORDATA 

or slate gray. That these are not different species is proved by the fact that 
occasionally one or two "blue foxes" occur in the litter where all the rest 
become white; for all the young are blue. The arctic fox is valued for its 
fur. The blue variety, being less abundant, is worth twice that of the white. 
Commercial companies are, therefore, making attempts to breed these foxes 
on the islands of the Alaska coast. In the extreme north the arctic fox 
stores its food in summer for the long, desolate winter. There are a number 
of other species of foxes. 

The wolf-like dogs include the dogs, jackals, and wolves. Domestic dogs 
of to-day comprise about two hundred breeds. They are owned by natives 
of all countries except the South Sea Islands. They have been associated 
with man for thousands of years, their remains having been found in Danish 
kitchen-middens, in the Swiss lake-dwellings, and in the remains of the 
Bronze Age in Europe generally. It is only since the invention of firearms 
that hunting with dogs has become general, as stealth was necessary to the 
successful hunter and the dog might frighten the game. It might have been 
used in running down such animals as the deer, but it seems from obtainable 
evidence that it was used for the protection of the camp, to watch while the 
master slept, and to give the alarm if beast or man came near; or it served as 
food in time of necessity. Authorities vary in their opinion as to what stock 
gave rise to the domestic races. " The jackal, bunasu, and the Indian wolf 
have been suggested as ancestors. It is probable there has been much 
mixture and that different wild types have been selected by man in various 
countries. "1 The intelligence of dogs and their ability to learn by training 
are well known and utilized by breeders and dealers. 

There are many species of African and Oriental jackals. Some feed 
chiefly on carrion, but also commit depredations upon the hen roosts and 
farmyards; others live upon figs, and others chiefly upon fruits. Their cry 
is a long howl, ending in a series of short yelps. Anderson says "they often 
congregate near one's tent and make the night hideous with their howls." 

The wolf of the present time is distributed over most of Europe, northern 
Asia, and North America, wherever a rough country affords it shelter. 

Hornaday says "there is no depth of meanness, treachery, or cruelty to 
which they do not cheerfully descend. They are the only animals on earth 
which make a regular practice of killing and eating their companions and 
devouring their own dead. But in the face of foes capable of defense even 
gray wolves are rank cowards, and, unless cornered in a den, will not stop 
to fight for their own cubs." The five or more sooty brown whelps are bom 
in a cave (which is often dug by the mother) early in May, but usually only 
two or three survive. In winter wolves form a pack to assist each other in 
attacking the prey. Travellers through infested regions have been boldly 
pursued and killed by them. The prolonged deep-chested bass howl, which 
"multiplies itself by its rapid echoing until one woK sounds like a dozen," 
is not broken into a bark like that of the coyote. The timber or gray wolf 
(Canis occidentalis) is very much like the European (C lupus) . It can adapt 
itself to almost any situation, being at home in the timbered regions or on the 
treeless prairies of the West, in the evergreen or on the treeless prairies of 
the West, in the evergreen forests of British Columbia, and on the desolate 
barren ground of arctic America. Its winter coat is long and shaggy, and 
varies from the standard gray (black and white mixed) to black in Florida 
and rufous in Texas, while in the North it varies from black to the predomi- 
nating white color of arctic animals. 

1 Beddard, p. 423. 



MAMMALIA 



363 



The coyote (C. latrans) (Fig. 292) of the western plains is one-third smaller 
than the gray wolf, and carries the tail low, as befits a coward, while that of 
the wolf points above the horizon. The cry is a dog-like yelp, half howl, 
half bark. They feed upon prairie-dogs, ground squirrels, sage grouse, and 
rabbits, and, probably, sheep and pigs. They are not dangerous to man. 
The five to seven puppies are born in deep holes or washouts in the banks of 
streams in May. 

The cat family (Fe'lidoe) includes lions, tigers, cats, and the hunting leop- 
ards. The distribution is worldwide, with the exception of Australia and a 
good deal of the Australian region. In genus Felis the claws are retractile. 

The lion {F..leo) differs from air others by the possession of a mane by 
the adult male. The largest lions come from south Africa. The adult is 
uniform pale tawnish or yellowish gray. The young is spotted. It inhab- 
its Africa, India, parts of western Asia, and formerly ranged into Europe. 




Fig. 292.— Coyote. (Circular 63, Biologic Survey, U. S. D. A., April, 1908.) 

It is mainly nocturnal in its habits, though it often feeds in daytime or at 
dusk, as the animals go to the spring for water. It feeds on anything it 
can capture, or even on carrion. The male may hunt alone, while his mate 
cares for the two to five whelps or cubs in some dense cover, bringing the 
food to his mate. It is said, however, that the males eat at the first table, 
leaving the rest of the family to take what is left. When the cubs are old 
enough the mother joins in the search for prey, which is usually obtained 
by "stalking," that is, by stealthily creeping up through the tall grass and 
leaping upon it, striking a fell blow, and clutching it with claws and teeth. 
Failing in this., they sometimes give chase. Lions cannot climb trees. 
"The choice of mate seems to lie with the female," says Ingersoll, "and 
the continuance of the union appears to depend on the power of the lion to 
hold his fickle spouse to her allegiance." She tries to flirt with every 
new male, but her mate bounds between her and the intruder and then 



364 BRANCH CHORDATA 

ensues a fierce struggle for possession unless the intruder slinks away. 
The female fawns upon the conqueror, whichever he may be. There is 
some, though insufficient, evidence, that the male is sometimes a polyg- 
amist. Lions will live for thirty or forty years and breed well in captivity. 

The tiger (F. tigris) is about the same size as the lion, the female being 
12 or 15 inches shorter than the male. He is more quick, sly, subtle, and 
cunning. The tiger is exclusively Asiatic, ranging northward, even into icy 
Siberia. Tigers are creatures of the mountains rather than the open plains. 
The northern ones are adapted to the cold climate by longer and closer fur. 
Tigers can climb trees and can swim considerably. Naturally, they hunt in 
the evening or night, but extreme hunger may drive them to hunt in day- 
time. The Malays and Hindus hold them in superstitious terror and oppose 
their destruction. 

The leopard or panther {F. pardus) is both African and Asiatic. It 
varies from almost black to a tawny color. It is spotted with small rosettes 
or rings of black surrounding spots of light or tawny color. Some of the 
spots are solid black. It is as ferocious as a tiger, but sly and cautious, and 
far lighter and more active. It can climb a tree like a cat. It necessarily 
preys upon smaller animals than do lions and tigers, playing havoc with 
poultry, sheep, goats, dogs, wild birds, monkeys, and wild pigs. Carrion 
also furnishes it food. Its cry is a " harsh, measured, coughing roar." The 
snow leopard or ounce {F. undo) is a beautiful creature, white, with larger 
black spots. It is confined to the highlands of central Asia. 

The jaguar {F. onca) is the largest and handsomest of the American cats. 
The head is large and the tail short. It has a golden-yellow coat, marked on 
the back and sides with large black rosettes, between which run the narrow 
lines of yellow ground color. The spots on the legs, head, and under parts 
are solid black. It is found in South America, Mexico, and as far north as 
Texas. Hornaday believes that it has the strongest jaws of any member of 
the cat family. It is fierce, powerful, and dangerous, but is afraid of man. 
It also climbs trees. 

The puma {F. concolor) is found in "all the great western mountain-ranges 
and in many tracts of the bad lands of Wyoming and Montana, in British 
Columbia, in the Adirondacks and Florida," and south to Patagonia. 
Hornaday says that although the puma has been known ' 'to follow belated 
hunters out of curiosity, this animal is less to be dreaded than a savage dog." 
It sometimes screams like a terrified woman or boy ; it always flees from man 
if there is a way of escape. It is a thin, tall animal of a brownish drab color. 

The lynxes of North America are "short-tailed, heavily furred, tree- 
climbing cats," distributed over nearly all the wild portions of the country 
north of Mexico, whether forests, mountains, plains, canyons, or even 
deserts. They are neither courageous nor pugnacious unless cornered. 
The Canada lynx (L. canadensis) has a long pencil of stiff black hairs rising 
from the tip of each ear. It has large, hairy paws, and is a good climber. 
It swims well, but runs rather poorly on land. A full-grown one weighs 
22 pounds. There are two young. The Bay lynx, or wild-cat, is usually a 
mixture of rusty red, gray, and blackish brown, with red prevailing. It 
is found in both the East and West and in Texas. No lynxes are found in 
the lowlands of tropical or South America. 

The domestic cat, says Beddard, is regarded as the descendant of the 
eastern F. caffra or the closely allied F. maniculata, or from both and from 
their interbreeding with the wild-cat of Europe, for many species of cats, 
even the lion and tiger, it is said, will interbreed. Whatever was the source, 
they have been crossed and interbred with many varieties before reaching 



MAMMALIA 365 

the " house cat " of to-day. The domestication of the cat is very remote. 
A tablet dating from 1600 B. c. has on it the representation of a cat. 
" Rows of skilfully wrapped mummies of cats in richly adorned cases" may 
be seen at Cairo, showing that ancient Egyptians must have held them 
in reverence. 

The hunting leopard {Cynoelu'rus jubatus), of Africa, India, Persia, and 
Turkestan, has longer legs and less retractile claws than the true cats. In 
India it has been trained for ages to capture game for its masters. 

The civets ( Viver'ridoe) are comparatively small animals, with usually 
five digits and with non-retractile or very incompletely retractile claws. 
There is usually a scent gland, which is the source of the civet perfume. 

The Tracker (Herpes'tes ichneu'mon), or "Pharaoh's rat," is the size of a 
cat with dark gray color. It destroys the eggs of crocodiles, lizards, and 
snakes. H. gris'eus (Mongoose) destroys the Cobra. 

The genus hyena (Hyen'idce) comprises three living species. The body 
is bulky, the legs strong, the head big and dog-like, and the jaws strong. 
They are nocturnal scavengers, though sometimes seizing small animals. 
They are found in Europe, Asia, and Africa, but not in America. 

Geologic Distribution. — "The first Carnivores appear in the 
order Creodon'ta, plantigrade forms of shghtly differentiated 
dentition (no carnassials) ; they present marked resemblances to 
marsupials, insectivores, as well as to the Condylar'thra, the an- 
cestral ungulates."^ There is a long gap, both in time and 
structure, between the few Eocene carnivores and their supposed 
ancestors among the Creodonts, which are generalized types 
as hinted above. In the late Miocene the present groups 
of Carnivora become more or less distinct by the intermediate 
" stock forms becoming extinct." 

Use to ilfan.— Hundreds of lion skins are sold annually, 
thousands of wild-cat skins, and more than a million skins of the 
common cat are made into cheap furs. 

The aquatic carnivora (Pinnipe'dia) include the seals, sea- 
lions, and walruses. They have acquired a somewhat fish-like 
form. The limbs are flattened into broad flippers, the five 
long toes are webbed, and the nails are often rudimentary. 
Molars and premolars are similar (carnassial absent). 

The northern fur seal {Ota'ria ursina) and the Patagonian maned sea-lion 
(0. jubata) belong to the genus Otaria, which is mainly antarctic. The har- 
bor seal is the common form along the Atlantic Coast. There is a colony 
of sea-lions on the Pacific. In the fur seals there is a dense, soft under fur. 
The Alaska seal has its summer residence and breeding grounds in one or 
two islands of the Behring Sea. In winter they are absent from these 
islands, and "their whereabouts is a matter of much speculation." They 
live in groups, consisting of a single old male and five to twenty females. 
The young males a year or two old herd by themselves, maturing at the 

^ Hertwig. 



366 BRANCH CHORDATA 

age of six. The females mature younger. The males are six or eight times 
as large as the females. The rivalry between the males is intense. In the 
fighting, great strength of neck and jaw is used. The fur seal industry rep- 
resents many millions of dollars. ^ 

The walrus family {Trichech'idce) belongs to the aquatic carnivores. The 
walrus is arctic and circumpolar. It is characterized by the enormous 
canines of the upper jaw, which form tusks sometimes 30 inches long. The 
walrus is from 10 to 12 feet long, and, though it can move about on land, it 
is very ungainly. The hair is short and scanty. As in the true seals, there 
are no external ears. The flesh, fat, and hide are much used in the North. 

The true seals {Pho'cidoe) have the nostrils in a dorsal position and have 
no external ears. The hind limbs are bound up with the tail and are useless 
on land. The largest is the elephant seal, about 20 feet long. The male 
has a proboscis of about 15 inches. This seal is mild and inoffensive except 
when enraged, and, of course, during the breeding season. The whole 
animal is invested in a mass of blubber which is as thick as that in a whale. 

Order IX. Insectiv'ora. — These are small, plantigrade, long- 
snouted, chiefly nocturnal mammals, which feed on insects and 
earthworms. The eyes are small or hidden by fur. The clav- 
icle is usually present; the cecum, absent or minute. As a rule, 
there are five digits. All of this order are provided with sharp 
teeth. The front teeth in both jaws are inclined outward, being 
less adapted for seizing the prey. The brain is of simple struc- 
ture, • the hemispheres usually smooth. 

Hedgehogs are covered with spines, but they are not barbed as in the 
porcupine, and they are firmly attached. Hedgehogs feed upon insects, 
chickens, young game birds, and even vipers. They are less than a foot in 
length, about the size of a big rat. They disappear in hot weather, and come 
out in rainy weather. They hibernate in winter. E. europoeus defends it- 
self by rolling up into a ball, with its head tucked between its fore feet and 
the hind feet drawn up close together, thus presenting, on all sides, its sharp 
spines to its enemies, few of which will attack the hedgehog. Pledgehogs 
are not found in the Western Hemisphere. Their voice is described as a 
sound between a grunt and a squeak. 

The shrews (Soric'idts) (Fig. 293) are small, nocturnal, f ur-covei ed in- 
sectivores, which are often mistaken for mice, but the teeth show they are 
not rodents. They are of wide distribution, but are not found in Australia 
nor in South America. Several species are found in the United States. 
S. personatus is chestnut brown, with large ears and short tail. They are 
thinly covered with hair. Their length is 2| inches; the tail, 1 inch. They 
are found from Massachusetts to Alaska. The water shrew (S. palustris) 
is the largest of our shrews, measuring 6 inches, with the tail 2\ inches long. 
The lesser shrews of Great Britain are burrowing, nocturnal animals, and 
secrete a disagreeable odor for protection. They are among the smallest 
of all mammals. 

1 See Hornaday, or Jordan's "Report of the Fur Seal Investigation," 
1896-97. 



MAMMALIA 



367 



The moles {Tal'pidce) are subterranean animals, with bioad front feet 
and vestigial eyes. The common prairie mole (Scalops aquaticus machrinus) 
(Fig. 294) is well known by its habit of bm-rowing in gardens for earthworms 
and grubs. It eats also the roots of vegetables. Its powerful front limbs 
are clawed for digging. Its hind limbs are weak, the tail short, and the nose 
pointed. The star-nosed mole of the eastern United States {Condylu'ra 




Fig. 293. — Common shrew. (After Coues.) 

cristola) has the tip of its snout encircled with fleshy projections. Talpa is 
an Old World form. The Russian Desman (M yog' ale moscata) hves in 
burrows in the banks of streams. It feeds on fresh-water msects and larvae. 
An Oriental insectivore is an aberrant form. It is much larger than most 
of the order and has an integumentary membrane, connecting the neck with 
the fore limb, the fore limb with the hind limb and the hind limb with the 
tail. 




Fig. 294. — Common mole (Scalops aquaticus), Linn. (After Coues.) 

Geographic Distribution. — This order is represented in every 
region except South America and Australia. The moles are 
confined to the temperate regions of the Northern Hemisphere. 
Hedgehogs are not found in the Western Hemisphere nor in 
Australia. 



368 



BRANCH CHORDATA 



Geologic Distribution. — In North America they date back to 
the Eocene Period. The Miocene Paloeoerina' ceus differs so 
httle from the existing genus, Erina'ceus, that the latter may be 
called " one of the oldest living genera of mammals." 

Use to Man. — Many mammals of this order have fine soft 
fur. They are also of value as insect destroyers. A single mole 
is said to devour twenty thousand insects annually. 

Order X. Chiroptera. — The bats have many points of resem- 
blance and structure with both lemurs and insectivores. But 
they are distinguishable from all other mammals by their power 




Fig. 295. — Skeleton of pteropus: /Si, Sternum; Ci, clavicle; Sc, scapula; 
H, humerus; R, radius; U, ulna; D, thumb; Jl, ilium; P, pubis; Js, 
ischium; Fe, femur; T, tibia; F, fibula. (After Owen.) 

of zigzag flight. " The wings " (Fig. 295) consist of an integu- 
mental membrane, supported by the digits (two to five), which 
are greatly elongated and are folded together like the ribs of an 
umbrella when the wings are folded. A membrane between the 
hind legs and tail, when present, is used for steering. 

The expanse of wing, compared with that of the body, is 
greater than that of most birds, but the muscles are weaker. 
The first digit, or thumb, is short, free, and strongly clawed, 
" and sometimes a sucker, by which bats scramble about rocks 
and trees, recalls the similar organ in that primitive lizard-like 



MAMMALIA 369 

bird, the Archceopterix.^' The bones of this order are slender 
and hght. The skull and teeth present many extraordinary 
variations. The radius is long and curved, the ulna is rudiment- 
ary, and the knee is directed backward. The sternum is keeled 
for the attachment of the pectoral muscles, the chief muscles of 
flight. The ribs are flat and sometimes ankylosed together by 
their margins. The fibula is rarely fully developed. The hind 
limbs are small and serve as a means of hanging the body head 
downward in rest or sleep, but are almost useless for walking. 
The skull is almost as large as the chest. The ears are sometimes 
much longer than the head. The nostrils are wide and are often 
surrounded by highly complicated sensitive membranes, which 
sometimes give the face a comical or even hideous expression. 
These are often more strongly developed in the male. The cheek 
teeth of the insectivorous bats terminate in sharp points, and 
are designed for cutting to pieces the hard parts of hard-shelled 
insects. The fruit-eating bats have molars with rather smooth 
crowns, while the vampires (Fig. 296, p. 371) have molars 
with scissor-edges and large canine teeth with sharp, cutting 
edges. The eyes are minute except in the fox bats. The wing 
membranes are sensitive, containing intricate network of blood- 
vessels, nerves, and " end organs," and thus, by the aid of their 
sensitive wings and sensitive membranes on the face, bats are 
enabled to fly without touching bodies in their way, though they 
be in utter darkness or when their eyes are so minute and fur- 
buried that they could not detect the intruding object. The 
cerebral hemispheres are smooth and do not extend over the cere- 
bellum. Bats are small and nocturnal and generally insectiv- 
orous, generally feeding on the wing, thus they are beneficial. 
Some are fruit-eating, and others, as the vampires of South 
America, are blood-sucking, attacking warm-blooded animals, 
and will even withdraw a quantity of blood from a sleeping man. 
There is nothing whatever to fear from the bats of the United 
States, for their claws and teeth are weak. The fur is usually 
brown or gray, " but a few Oriental species are mottled or varie- 
gated with orange, bright yellow and black," as is shown by 
the " painted " bat of Ceylon. This bat hides by day in the 
folded leaf of a plantain, and when disturbed, looks more like a 
butterfly than a bat. Mr. Swinhoe, a naturalist long residing 
24 



370 BRANCH CHORDATA 

in China/ says that these colors are highly protective, for the 
brilliant bat inhabiting Formosa resorts to the longan tree. 
This evergreen tree always has some portion of its foliage decay- 
ing, making these dying leaves orange and black, while the fruit 
is reddish yellow. Thus the orange and black bat, suspended 
from the branches, is concealed from its enemies by its protect- 
ive resemblance. Owing to their nocturnal habits very little 
is known of the activities of bats. " Wek:now that in the winter 
some of our species live in caves in a semidormant condition," 
and Dr. Hart Merriam has proved that some species do migrate 
in fall and spring. All bats living within the snow limit of the 
Temperate Zone must either migrate or hibernate, for the fruit- 
eating bats could find no food, and the delicate wings of the 
vampire, which might find food, would be frozen stiff in zero 
weather, so the latter are chiefly tropical. Bats usually inhabit 
caves, a million sometimes hibernating in one cave. The thick 
layer of guano on the floor of the cave may represent the deposit 
of centuries. Bat guano is a valuable fertilizer. In warm 
countries bats live in hollow trees. The cry is a shrill squeak. 
They are widely distributed, being found on islands where there 
are no other mammals. The occurrence of the same genus of 
bats in India and Madagascar has led some to believe that there 
must have been at one time some connection between these 
countries, as these slow-flying creatures could hardly have 
traversed these vast stretches of ocean by their power of flight 
alone.^ However, Hornaday tells of a British long-eared bat 
which was found clinging to the rail of an Atlantic steamer 30 
miles from land, with no breeze going from the land. 

Bats are divided into two groups: the large diurnal {Meg'a- 
chirop'tera), or fruit-eating bats, and the nocturnal {Mi'cro- 
cJdrop'lera), or insect-eating bats. "Many bats have a strong 
musky odor, due to secretion of certain glands in the skin."— 
Weysse. 

Megachiroptera. — The ordinary fruit bats or fox bats number about forty 
species. The fur is fox red, the muzzle long and pointed. The eyes are 
big and the ears upright, giving them a fox-like appearance. They live in 
colonies of from five to fifty. Hornaday killed some having 40 inches 
spread of wings. He says "of all creatures that fly, none are so uncanny 
when outlined against the sky as the big black-winged, half-naked flying 
fox (bats). They suggest demons and calamities." The fruit-growers of 

1 Ingersoll, p. 63. ^ Beddard, p. 525. 



MAMMALIA 371 



SfrT. 'li^ ww^^ Of their introduction into the United States, have 
f?,Ti^! T^^v^-P'"''^'^'*'''^u-^f'' importation even into zoological gardens. 
In the Ethiopian region this family is represented by the large, grotesque 
hammer-headed bat (Epomaph'orus). Its head, particularly the muzzle S 
enlarged, giving it a resemblance, in profile, to the head of a moose The 
larger fruit bats are eaten by natives of their countries and even relished by 
white men. They make affectionate pets, but it would seem strange, weird 

«lr!^!f™*'^'?-P*^'"l '^u^'^t^ ^^^ families. Here belong the leaf-nosed bats 
?fe /pfif T.t'^' *^' bonneted bats," and the naked bats, the vampires 
fS ^f ^1', ^"^ *^« common smaller bats. The naked bats of Borneo have 
fw-^ f ^^thery, elastic skm. A scent gland for defense is situated between 
iri '/^°^V^^ "''^- • 7^"" °^°^^ remarkable thing is the mammary 
pouch under each arm— a wide pouch of rubber-like skin in which the young 
are carried until able to fly. The mammary gland is in the lower portion of 




Fig. 296.— Head of Phyllos'toma (Vmnpyrus) spectrum. (Glaus.) 

KU?^?^ vampires or blood-suckers, the javelin bat iPhylos'toma hastatum) 
bites horses, cattle and even sleeping man. The sharp-edged, dagger-like 
teeth make a small round hole in the skin, from which the vampire draws 
K f K *? by mouth suction. The blood sometimes flows freely after the 
bat has left its victim, but there is no poison attending a wound The 
digestive organs of the vampires are extremely modified, these bats living 
upon predigested liquid food. The gullet is too narrow for any solid food to 
pass through and the stomach is intestine-like. 

The common bats {Vespertmon' idee) range overall parts of the world and 
number over two hundred species. Most of the bats of the United States, 
«Wa\!!! It fPecies, belong to this family. They are very common 
along the Atlantic coast and there are several species along the Pacific 
The commonest is the little red bat, which flies about in the early twilight' 
It IS constantly on the wing from sunset until dark. In its flight it can turn 
abruptly and with great accuracy. It is remarkable that it can turn and 
double so qmckly and dart in all possible directions without striking any- 
^f^' JK^^'■^^u^''a°^ the northeastern United States and Canada and the 
big-eared bat of the South Atlantic coast are members of this family The 
North American bats never make any nests. The little bats are born in 
crannies and, from the first, cling about the mother's neck when she 
chases the "numberless little flying things of the dusk. When there are 
twins, the male takes his share of the responsibility " 



372 BRANCH CHORDATA 

Geologic Distribution. — Bats appear for the first time in the 
Eocene Epoch, according to the records of the rocks.^ 

Order XI. Prima'tes. — This order includes all animals with 
hands and hand-like feet. With but a few exceptions the 
members of this order inhabit the tropics. Except in man, they 
reach their highest development near the equator. Hornaday 
says that there is no human being of sound mind to whom the 
human likeness of the lower Primates does not appeal. They 
are, at any rate, very much like man in their structural develop- 
ment. As a rule, they have five fingers and toes, each covered 
at the tip by a flat nail. The inner finger or toe, or both, are 
opposable, making the hand, and often the foot, a grasping organ. 
The feet are plantigrade. The limbs are quite free from the 
body, as compared with those of other chordates. The skull of 
the Anthropoi'dea is characterized by the bony partition between 
the orbital and temporal vacuities. The stomach is simple. 
The cecum is always present and sometimes large. They are 
chiefly arboreal, except terrestrial man. 

The sub-order Lemuroi'dea includes the aye-aye, tarsier, and 
the lemurs. The head lacks the human-like expression, being 
more like a fox, with a sharp muzzle. There are no cheek 
pouches. The tail, which is never prehensile, varies from none, 
in Loris, to the long and bushy tail of the " aye-aye." The 
thumb and great toe are well developed and the second toe has 
a sharp nail unlike the flat nail of the other digits. The brain 
case is small and the temporal and orbital fossae are in com- 
munication. The placenta is non-deciduate. The vermiform 
appendix is never present and the cecum varies in length. 
They are now found only in Madagascar, tropical Africa, and the 
Orient. In the Tertiary Period the ancestors of these animals 
were scattered all over the globe. 

The lemurs (Lemur' idoe) have round heads with fox-Uke muzzles, small 
ears, and a long tail (Fig. 297). The wooly fur, which is often beautifully 
tinted, is soft and thick. In size they vary from that of the squirrel to that 
of the cat. They are omnivorous, and, as a rule, diurnal or crepuscular. 
They are found in Madagascar. In trees they run about on all fours, but on 
the ground they walk erect on their hind legs. The one or two young are 
carried about by the mother as they cling to her breasts, or, later, ride upon 
her back. One of the most interesting is the ring-tailed lemur, which 

1 Scott's " Geology," p. 506. 



MAMMALIA 



373 



scrambles over the rocks, its leathery palms being furrowed with sucker- 
like grooves, enabling it to go where man cannot. The ruffed or black and 
white lemur is perhaps the most beautiful. It is the size of a large house cat, 
has a long tail, and is clothed in long, soft, silky, fine fur. The mouse lemurs, 
dwarf lemurs, and fat-tailed lemurs estivate during the hot and dry seasons, 
curling up in their nests, just as northern animals do in hibernation. 
"They go in fat, subsist by absorption of this stored tissue, and come out 
thin and weak" at the approach of the rainy season. Lemurs are all per- 
fectly harmless, but their weird actions, big eyes, and loud cries have led to 
their being reverenced and feared by the superstitious natives. 

The female aye-aye constructs a 
globular nest in a tree for the rearing 
of her single offspring. 

Sub-order Anthropoidea differs 
from the lemurs in having the 
mammary glands always tho- 
racic, the orbital and temporal 
fossae separated by bone. The 
cerebral hemispheres are highly 
developed, almost or quite con- 
cealing the cerebellum. There 
are over two hundred tropical 
and subtropical species. 

American monkeys (Platyrrhi'na) 
differ from the Old World forms in 
having the nostrils directed downward 
and separated by a broad septum. 
As a rule, they are also smaller and 
have but thirty-two teeth. The tails 
are usually long and prehensile. No 
American form has cheek pouches. 
Most of them are arboreal. All 
American monkeys are small, varying 
in _ size from that of young kittens or 
chipmunks to 20 inches long. They 
are hairy or woolly. One baby mon- 
key is born to each female each year. 

The marmosets are lowest in the scale of development, indeed, they 
sometimes look very little like monkeys. They range from southern 
Mexico to southern Brazil. They are small, delicate creatures, with hair- 
less faces, large, bright eyes, and long tails. In some species the long silky 
hair stands up on the head like a white ruff. The digits are, for the most 
part, clawed, the great toe only bearing a flat nail. They are arboreal, but 
the tails are not prehensile. 

The second family of American monkeys {Ceb'idce) is distinguished from 
the marmosets by thirty-six teeth, and by the generally long and prehensile 
tail, which is naked on the under side of the end. 




Fig. 297. — Ololicnus galago of Af- 
rica. (From Vogt and Specht.) 



374 



BRANCH CHORDATA 



The Saki monkeys (Pithe'cia) of tropical South America east of the Andes 
have long, bushy, non-prehensile tails, and, sometimes, a long, black chin 
beard. 

The squirrel monkeys (Sai'miri) are little creatures with a long head, the 
occiput projecting. The proportions of the cranium, as compared with the 
face, are greater than in other monkeys or in man. They are gregarious and 
arboreal, feeding upon insects, small birds, and eggs. 

The howlers are the most hideous looking of the American monkeys and 
have the least intelligence. The brain is less convoluted than that of the 
At'eles. Their howl, made to intimidate enemies, can be heard two miles. 




Fig. 298. — Spider monkey. (American Museum of Natural History.) 



The natives hate the howlers and kill them for food, selling the hide to white 
traders. The hair is twisted into cordage. 

The spider monkey {Ateles) (Fig. 298) is the most typically arboreal 
of American monkeys. With its prehensile tail held erect over its head, it 
"feels" for a place to grasp, which it does by wrapping the end of its long 
slender tail tightly around the branch. It then swings itself far across 
toward another limb, which it grasps with its thumbless hands by hooking 
them around the limb and thus suspending its body. "They have a very 
uncanny look and can come as near tying themselves into a knot as any liv- 
ing mammal can." They are weak and cowardly. The Mexican spider 



MAMMALIA 375 

monkey is the most northern one in America, sometimes coming up to 
latitude 32°. 

Perhaps the most typical of this family is the genus Cebus of twenty 
species, ranging from Costa Rica to Paraguay. The common monkey 
of the organ-grinder belongs to this genus. The thumb is well developed 
The color is usually dull brown, but one is brick red and others have white 
about the shoulders. They are gregarious. Contrary to the general belief 
. that they are strictly herbivorous, they are very fond of caterpillars. 

"No monkeys ascend high in the Andes nor reach the west coast, and none 
are found south of the forests of Brazil or north of south central Mexico. 
Fossil remains of monkeys are rare everywhere, and known in the New World 
only in the Santa Cruz Miocene formations of Patagonia; and they show 
no more kinship with the Old World types than do the existing species. "i 
Old World monkeys (Catarrhi'na) have the nostrils close together and 
directed downward. There are open cheek pouches and but thirty-two teeth. 
The tails are non-prehensile or even absent. Often there are hard patches 
of hairless, bright-colored skin (ischial collosities) upon the haunches. 
Catarrhine monkeys are larger and more intelligent than the Platyrrhine 
forms. These distinctions are ancient, "since no fossil remains of mon- 
keys at all intermediate have so far been discovered, another evidence of 
the very early time at which South America became isolated." 

Macaques and baboons (family Cer'copithec'idoe) contains eight or nine 
genera divided into two subfamilies. The first (Cer'copitheci'nce) consists 
of rather large monkeys represented by macaques and baboons. They have 
cheek pouches in which to store the food. All the macaques but one are 
Asiatic. They are from 13 inches to 3 feet long, the male being larger than 
the female, with larger canine teeth. They are gregarious, noisy, and active, 
scrambling about rocks, and some swim and dive well." In some parts of 
India they damage gardens. Their dog-like teeth and strong nails are able 
to inflict severe wounds. As examples, the bonnet monkey, the Gibraltar 
ape, and the pig-tailed monkey may be mentioned. The latter is trained 
by the natives to climb the cocoanut-palm tree and to select and throw down 
the ripe cocoanuts. 

The baboons (Cynoceph'alus) are found in Africa and Arabia. The 
African forms vary in size from that of a spaniel to that of a mastiff. 
Their stout limbs are about equal, the nose and head are dog-like, and the 
canine teeth long and sharp. They are the fiercest of all Primates. It is 
said that even a hungry lion will not attack a baboon. The great ischial 
collosities are strikingly colored, adding to the ugliness caused by overhang- 
ing eyebrows, small eyes, ferocious disposition, and filthy habits. It is 
said these collosities attract the kite bird, which mistakes them for raw meat, 
and the baboon makes a meal of the bird. The color is blackish or a green- 
ish or yellowish gray, grizzled by each hair being ringed with various colors. 
The Gelada has a black body and a brown mane, with a gray chest. It looks 
like a small lion with a baboon's hands and feet. Baboons like the open 
country and the rocky hills and deserts. They go in troops. 

The second sub-family (Semnopitheci'nae) includes guerezas, the langurs, 
or Asiatic holy apes, and the Bornean genus Nasalis. They are slender 
apes with no cheek pouches and have a sacculated stomach. 

The anthropoid apes (Simi'idce) , though chiefly arboreal, walk erect or 
semi-erect when they come to the ground. Their hands and feet are fitted 
for a half-arboreal, half-terrestrial life. When they put their hands to the 

^ Ingersoll, p. 37, 



376 



BRANCH CHORDATA 



ground to aid in walking they rest upon the back of the knuckles. Cheek 
pouches and tail are lacking and the hair is more scanLy than in the baboons. 
These entirely Old World forms have a vermiform appendix. 

The gibbons (Hylob'ates), slender, monkey-like Indo-Malayan forms, 
stand at the base of the series. They are the smallest and most arboreal 
and their arms are the longest of any of the group, being long enough 
to reach the ground even when standing erect. The canines are large in 
both sexes and the jaws and nose are prolonged. The brain is simpler than 
in the higher forms. One of the most remarkable habits is their descending 
flight through the trees, though they never come to the groimd. They leap 
incredible distances, says Hornaday, catch and swing with their hands, catch 
again with their feet, turning again, and so on, by a series of revolutions 
almost as fast as the flight of a bird. The largest is the Sumatran Siamang, 
which stands 3 feet tall and is shining black. The gray gibbons are very 
timid, but show strong affection for their young and great courage in their 
defense. 




Fig. 299. — Comparison of skeletons of primates: 1, Gibbon; 2, orang; 3, 
chimpanzee; 4, gorilla; 5, man. 



The brown orang-utan lives in Borneo and Sumatra, wholly in the 
tree-tops, coming to the ground only for water. On the ground it moves 
slowly and swings its body along between its arms like a pair of crutches. 
In the trees, too heavy for leaping, they swing underneath the branches with 
their long arms, "grasping a limb with their hook-like hands, and swinging 
underneath to the next hold, and so on, at great speed. "^ It subsists upon 
wild fruits, fleshy leaves, and shoots of the screw pine. It is shy and uncer- 
tain if captured. When young it is easily tamed; when grown, wild and 
ferocious. Hornaday says "in 1901 the zoological park contained four 
orangs, all of which were taught to wear clothes, sit in chairs at table, eat 
with fork and spoon, drink from cups and bottles, and perform many human- 
like actions without nervousness in the presence of two thousand visitors. 
Each of the orangs learned its part in about two weeks' training, and at the 

^ IngersoU. 



MAMMALIA 377 

dinnCT table acted with gravity and decorum." In captivity young oranga 
are affectionate as children and are fond of their human friends. At night 
the wild orang makes a nest to sleep upon by breaking off leafy branches 
and laying them crosswise m the forked top of a sapling, where it lies flat 
upon Its back, grasps the branch firmly in each hand and foot, and is rocked 
to sleep in the tree-top. 

The chimpanzee (Fig. 300) has a " brain, face, ears, and hands 
more man-Hke than those of any other ape." Its face, ears, 
hands, and feet are naked. It has a large brain and a higher 




Fig. 300.— The chimpanzee, variety Tshego. (From Brehm's "Thierleben.") 

intellect than any of the Primates below man. It is bright and 
cheerful and, having a good memory, is easily taught. The 
young are affectionate, but the old males are dangerous. There 
are at least two species. They are natives of Africa. Mated 
pairs seem to remain together permanently, and missionaries, 
when they tried to teach that polygamy was wrong, have been 
told by the natives " that they did not wish to be like apes." 
They spend much time hiding in thickets in family groups, 
sometimes gathering m such numbers as to do considerable 
damage to young bananas. They are crepuscular. They show 



378 



BRANCH CHORDATA 



great affection for their families, the father often taking the baby 
from the mother and carrying it, especially in dangerous places, 
and they seek to assist one another when hurt or in trouble. 
They seem to delight in noise, uttering loud shrieks and howls, 
and drumming with sticks on resonant logs. This is the only 
employment of an instrument or tool, and, in itself, shows a wide 
difference between the chimpanzee and the lowest human savage. 




Fig. 301. — Gorilla engena. (Vogt and Specht.) 



A rude platform of branches is built for the family bed, the 
father, perhaps, sleeping curled up in a crotch of the tree be- 
neath it. 

The Gorillas. — Both in kind and number "the bones below the 
skull are the same in the skeletons of man and the gorilla. 
They differ only in their proportions " (Fig. 299, 4). The widest 
differences are in the skulls. In the gorilla the high forehead 
and intellectual faculties so characteristic of man are entirely 



MAMMALIA 379 

wanting, indicating a low order of intelligence. " The long and 
powerful canine teeth are alone sufficient to proclaim the savage 
wild beast." The gorilla is not teachable like the chimpanzee, 
but is sulky and ferocious. The gorilla is the only ape that walks 
erect. Its arms are relatively short and its legs long. Its 
hands reach a little below the knees when standing erect. It 
has big feet and a pronounced heel. The digits are webbed.^ 
The brain is larger than that of the chimpanzee, but so is the 
body. The great similarity of structure to that of the human 
body is due largely to the plantigrade walk and the terrestrial 
life. The gorilla is more primitive than the chimpanzee and, 
therefore, nearer to the common ancestral stock. It is found in 
a small area in West Africa on the equator, and between the 
Gaboon and Congo Rivers. Hornaday declares that if the head 
of a chimpanzee were placed on the shoulders of a gorilla, we 
should have the " missing link," and that if the missing link 
is ever found, it will be in the " Tertiary deposits of the fertile 
uplands that lie between the gloomy equatorial forests of the 
black apes and the bushmen of South Africa." 

Man. — Fossil remains of a man-like ape, Anthropopithe'cus 
erectus, have been found in the upper Pliocene of Java. It is 
generally thought that these fragments belong to an exceed- 
ingly large gibbon-like animal having an enormous cranial 
cavity and a brain nearly equal in size to that of some of the 
savage races of man to-day. There is no doubt that man 
Uved on the earth at the beginnings of the Pleistocene times, 
and it is thought by many anthropologists that he lived in the 
latter part of the Tertiary Period, though this has not been 
satisfactorily proved. 

The family Hominidce contains but a single genus. Homo, 
and one species, H. sapiens. The different varieties of this 
species are now generally classified in three great groups: 
the Ethiopian, of Africa; the Mongolian, of Asia; and the Cau- 
casian, of Europe. Man is distinguished from other primates 
by a less development of hair on the body, by the erect walk, 
and by the consequent modification of the hind limbs and feet 
(he is a true biped). The face does not project so much as 
that of the anthropoid apes. The skull of man is a smooth, 
1 Beddard, p. 572. 



380 BRANCH CHORDATA 

rounded case, while that of the apes is smaller and deeply ridged 
and contains a smaller brain. Man's outstretched hand does 
not reach the knee and the thumb is much more useful. The 
hallux (great toe) is not opposable. There are no laryngeal 
pouches. " The minute diverticula, the ventricles of Morgagni, 
alone remain to testify of a former howling apparatus in the 
ancestors of man."^ 

Man has the power of articulate speech and the faculty of 
reason. As to whether this vast difference in reason be one 
of kind or degree, psychologists disagree, but all concede that 
the reasoning power of man is far in advance of that of any 
other animal. 

Man's superiority over animals lies in his highly developed 
powers of abstract thought, reason, and will. Through these 
powers he is able to adapt himself to his environment, make a 
new environment, or migrate to one better suited to his needs. 
He can control the lower forms of animal life and modify them 
by artificial selection and breeding to satisfy his wants. From 
them he procures clothing, leather, food, ornaments, weapons, 
fertilizer for his land, and materials used in his houses. He 
uses them as beasts of burden or as means of travel. Through 
undue use or slaughter he has caused the extinction of various 
species. 

The student has missed the greatest value of the study of 
zoology if he has not discovered that the great underlying 
principles which permeate and control all animal life from the 
lowest to the highest forms necessarily apply also to the life, 
development, and history of mankind. Descent with adaptive 
modifications is amply illustrated in the descendants of one 
man during his lifetime. The influence of environment, 
growth and decay, heredity, variation, adaptation, the survi- 
val of those best adapted to conditions in the physical or the 
business world, the strengthening of powers of body or mind 
by use, the degeneration of powers by dependence upon others, 
the sacrifice of the parent for the offspring everywhere seen in 
nature, or the triumph of altruism over egoism in the service 
of one's family or his fellow-men — -these are some of the bio- 
logic principles directly applicable to man. 
1 Beddard, p. 589. 



MAMMALIA 



381 



Classification. — 

Order. 
I. Monotrem'ata. 
II. Marsupia'lia. 

III. Edenta'ta. 

IV. Sire'nia. 
V. Ceta'cea. 

VI. Ungula'ta. 

VII. Roden'tia. 

VIII. Carniv'ora. 

IX. Insectiv'ora. 

X. Chirop'tera. 

XI. Prima'tes. 



Examples. 
Duckbill, Spiny Ant-eater. 
Kangaroo, Opossum. 
Ant-eater, Armadillo. 
Manatee, Dugong. 
Whales, Porpoises. 
Cattle, Sheep, Deer, Horses. 
Rabbits, Squirrels, Prairie-dogs. 
Cats, Dogs. 
Moles, Shrews. 
Bats. 
Apes, Monkeys, Man. 



THEORIES OF DEVELOPMENT 

Origin of Life. — Many scientists to-day advocate that life 
is the action of chemical and physical forces in connection with 
a peculiar substance called protoplasm. But no one has yet 
been able to explain all the phenomena of life by means of these 
forces. Until this is done, we must believe that life from life 
is the universal rule, or that no living organism originates except 
from some pre-existing living form. 

Protoplasm is the physical basis of all life, both plant and 
animal, and without this complex substance life cannot exist. 
It is a protein which is known only as a product of living sub- 
stances.^ It is chemically and physically unstable, but it is 
impossible to obtain a satisfactory chemical analysis since the 
dead material differs from the living protoplasm both in its 
power and structure. 

There is little direct proof of the character of life in the 
Archaean Era, but it must have been marine. Since plants 
usually feed upon inorganic matter and animals cannot manu- 
facture organic compounds from inorganic ones, and as plant 
life is thus a necessity for the existence of animal life, it is 
thought that plant life may have been first. However, the 
view that plant and animal forms originated side by side and 
have developed along diverging lines is common. 

Since the simplest form of life to-day consists of a single cell, 
it is believed that primitive life began as a single cell. 

The Cell Theory. — Cells were first described by Hooke, an 
Englishman, in 1665, and were so named from the resemblance 
of the compartments in the structure of a piece of cork to the 
cells in a monastery. Schleiden, in 1838, showed that plants 
were composed of cells, and in 1839 Schwann discovered the 
same general fact concerning the bodies of animals, thus re- 
vealing the common plan of organization of plants and animals. 

The cell theory involves: (1) that all organisms are made up 
1 McFarland's " Biology." 
382 



CELL DIVISION OR MITOSIS 383 

of single cells or combinations of cells; (2) that all organisms 
begm life as a smgle cell, giving rise in metazoans to a body of 
more or less complexity, and (3) that the function of this com- 
plex (multicellular) organism may be expressed in terms of the 
activities of the individual cells of which it is composed. The 
third proposition may need some modification. "It was 
through the cell theory that Kolliker, Remak, Nageli, and 
Hofmeister opened the way to an understanding of the nature of 
embryologic development, and the law of genetic continuity 
lying at the basis of inheritance. It was the cell theory again 
which, m the hands of Goodsir, Virchow, and Max Schultze 
inaugurated a new era in the history of physiology and pathol- 
ogy, by showing that all the various functions of the body, in 
health and in disease, are but the outward expressions of cell 
activities. And at a still later day it was through the cell 
theory that Hertwig, Fol, Van Beneden, and Strasburger solved 
the long-standing riddle of the fertilization of the egg and the 
mechanism of hereditary transmission. No other biologic 
generalization, save only the theory of organic evolution, has 
brought so many apparently diverse phenomena under a com- 
mon point of view, or has accomplished more for the unification 
of knowledge. The cell theory must, therefore, be placed be- 
side the evolution theory as one of the foundation stones of 
modern biology."^ 

Cell Structure.— In the typical cell are found the following 
parts: (1) the cell wall; (2) the cytoplasm, or cell substance, 
which includes the plasma (that is, the living protoplasm around 
the nucleus) and the chylema, or "cell-sap"; (3) a nucleus which 
is usually inclosed by a delicate membrane, and which contains 
chromatin and achromatin fibers and one or more nucleoli, and 
(4) one or two centrosomes or attraction spheres. 

Cell Division or Mitosis.— The centrosome divides into two 
parts, which gradually separate, and each of which becomes the 
center of a system of fine achromatin fibers radiating about it 
A spindle of achromatin fibers is also extended from one centro- 
some to the other. At the same time the chromatin granules 
scattered throughout the nucleus are arranged into a continu- 
ous thread or skem of closely contorted filaments. The nuclear 
1 Wilson, "The Cell." 



384 THEORIES OF DEVELOPMENT 

membrane generally disintegrates and the chromatin thread is 
broken up into U-shaped fragments (chromosomes). These 
U-shaped chromosomes are arranged as the equatorial plate 
half-way between the centrosomes and across the axis of the 
spindle. Either before or after the formation of the equatorial 
plate the chromosomes split longitudinally, so that each part 
contains an equal amount of the chromatin. The chromosomes 
now move along the spindle (or its fibers contract), so that one- 
half of each original chromosome is drawn to one centrosome 
and the other half to the other centrosome. These chromo- 
somes, with their apexes pointing toward the center, are now 
arranged about their respective centrosomes. The protoplasm 
of the general cell becomes constricted in the center, each group 
of chromatin loops rearranges itself into a nucleus like that of 
the mother cell, and an investing membrane becomes ap- 
parent. A furrow appears on the surface of the protoplasm and 
gradually deepens until the protoplasm is divided into two equal 
segments, each containing its own nucleus and centrosome and 
being a complete daughter-cell. 

Maturation. — Metazoans usually reproduce by means of 
fertilized eggs or ova. Egg cells vary in size from less than yIt 
to about 1^0 inch in diameter. By this is meant the minute 
germ cell without the enormous amount of nutritive material 
which usually accompanies it. 

Before the process of fertilization takes place (about the 
time of the entrance of the spermatozoon, which, however, 
takes no part in the process) the ovum undergoes a process of 
maturation, in which one-half of the number of chromosomes is 
thrown off. A spindle-shaped structure is formed from minute 
fibers in the cytoplasm. The centrosomes, one at each pole of 
the spindle, seem to control its formation and activities. This 
spindle draws from the egg nucleus a definite number of chro- 
mosomes which are arranged across the center of the spindle, 
which now moves endwise toward the surface of the egg. A 
small protrusion is made, the spindle divides across the center, 
and the first polar cell, consisting of a nucleus with chromo- 
somes and a small amount of cytoplasm, is formed and thrown 
off. The remaining portion of the spindle disappears. The 
other centrosome divides into two and forms another spindle, 



SEGMENTATION 385 

on which the chromosomes are again arranged as before, and 
the second polar cell is formed. These polar cells disintegrate. 
The nucleus of the ovum now contains only about half the 
number of chromosomes present before the process of throwing 
off the polar bodies. This remaining portion of the nucleus 
retires from the circumference and is called the female pro- 
nucleus, or macrogamete, which is ready for fertilization. The 
spermatozoon previous to entering- the ovum undergoes a 
similar reduction of chromosomes, though the resulting cells 
form sperms. 

Fertilization, — The enveloping membrane of the ovum con- 
tains one or more minute openings through which the sper- 
matozoon, or male germ cell, enters for the purpose of fertiliza- 
tion. The spermatozoon consists of a nucleus or extremely 
minute head, a centrosome, and a fiagellum or tail, which is 
for the purpose of locomotion and disappears upon the entrance 
of the spermatozoon into the ovum. The nucleus, called the 
male pronucleus or microgamete, enlarges, the centrosome 
divides, and a mitotic figure is formed which moves toward the 
female pronucleus, which moves toward the male pronucleus. 
Finally, male and female nuclei meet in the midst of the spindle 
formed about the male nucleus; thus the male and female 
nuclei are united into one nucleus or zygote. 

Segmentation. — This zygote or fertilized ovum now contains 
the normal number of chromosomes or "hereditary threads" 
for its species, one-half of which have been furnished by the 
maternal cell and one-half by the paternal cell. When the 
process of mitosis is completed, this zygote is divided into two 
daughter-cells, each containing the same number of chromo- 
somes, half of which have been derived from the sperm and half 
from the ovum. Each of these daughter-cells subdivides into 
two, and the resulting four, into eight cells, and so on, the num- 
ber varying with different species. When there is little or no 
yolk or nutritive material the whole egg divides equally; when 
there is much yolk the division is unequal or partial. 

Differentiation of Tissues. — From the ectoderm are produced 
the outer portion of the skin and its outgrowths and the whole 
nervous systeni; from the endoderm come the lining of the di- 
gestive tract and the essential parts of the glands connected with 

25 



386 THEORIES OF DEVELOPMENT 

it. The mesoderm gives rise to the bones and muscles, the cir- 
culatory system, and the muscular walls of the alimentary tube. 
All metazoans pass through these early stages of development, 
and embryology teaches that from these simple beginnings the 
most complex animal body is developed. 

This sphere of cells is known as the morula or mulberry stage 
(Fig. 5), and is succeeded by the blastula stage, in which the 
cells are arranged in a circle about a cavity filled with watery 
fluid. On account of inequalities, one portion of this sphere 
becomes pitted, this pitting-in grows deeper until there is a 
complete invagination of this portion, like the pushing in of one 
side of a hollow rubber ball until the two sides touch. This is 
called the gastrula stage, and occurs in all the main divisions 
of the animal kingdom. (In many vertebrates delamination 
supercedes or follows invagination, but this, perhaps, ''is a 
later development or, possibly, improvement upon gastrula- 
tion."^) This gastrula stage is an open sac composed of two 
layers of cells, the outer or ectoderm, and the inner or endoderm. 
In most cases a third mass of cells, the mesoderm or middle 
layer is formed, probably from the endoderm. The opening 
of this sac-like body becomes the primitive mouth. 

History and Theories of Evolution. — Evolution is not a new 
theory. Traces of such an idea are found in old Greek phil- 
osophy. Empedocles (about 500 b. c.) believed that "plants first 
sprang from the earth while the latter was in process of devel- 
opment. After them came the animals, their parts having 
first formed themselves independently and then been joined by 
love." After ceaseless trials, nature succeeded in producing 
fit tribes for perpetuation. Osborn says this is the germ of the 
"survival of the fittest." Aristotle (384-322 b. c), though 
believing in separate creation, taught vaguely that living beings 
formed a gradual succession from the "less to the more perfect." 
Aristotle laid great stress upon the inductive method of study, 
and he was so great an observer of animals as well as a collector 
of the statements of others concerning them that he has been 
called the founder of zoology. If only his principle — ^that "we 
must not accept a general principle from logic only, but must 
prove its application to fact; for it is in facts that we must 
1 Romanes' " Darwin and After Darwin." 



HISTORY AND THEORIES OF EVOLUTION 387 

seek general principles, and these must always accord with 
facts" — had been remembered and applied by him and his 
successors, science need not have progressed so slowly for so 
many centuries. 

The special creation theory interrupted scientific thought 
and investigation for many centuries. Philosophy preceded 
science in the line of evolutionary thought. Leibnitz, a German 
philosopher (1646-1716), believed that "living beings form an 
unbroken series from the simple to the complex, some steps in 
the series having become extinct."^ Buff on (1707-88) thought 
that organisms could be modified by changes in food and envi- 
ronment or by domestication, and that parts could be modified 
by disuse. He was one of the first to attempt an explanation 
of the geographic distribution of animals. 

Erasmus Darwin (1781-1802), grandfather of Charles 
Darwin, author of "The Origin of Species," was a physician and 
physiologist as well as a gardener and lover of plants. He 
thought that the various plants and animals were descended 
from "few ancestral forms or possibly from one and the same 
kind of vital filaments." He emphasized function, saying that 
''from their first rudiment or primordium to the termination 
of their lives all animals undergo perpetual transformations; 
which are in part produced by their own exertions in conse- 
quence of their desires and aversions, of their pleasures and their 
pains, or of irritations or of associations; and many of these 
acquired forms or propensities are transmitted to their poster- 
ity." 

Lamarck (1744-1829), although unappreciated in his own 
day, scientists of the present day, whether agreeing with him or 
not, admit to be one of the bravest of pioneers. Haeckel 
says "to Lamarck will remain the immortal glory of having for 
the first time established the theory of descent as an independ- 
ent, scientific generalization of the first order as the foundation 
of the whole of biology." To quote Lamarck, "Nature in all 
her work proceeds gradually and could not produce all animals 
at once. At first she formed only the simplest, and passed 
from these on to the most complex." He gives four laws as 
the summing up of his ideas: 

1 McFarland's "Biology." 



388 THEORIES OF DEVELOPMENT 

(1) ''Life by its inherent power tends continually to increase 
the volume of every living body, and to extend the dimensions 
of its parts up to a self-regulated limit. 

(2) "The production of a new organ in an animal body re- 
sults from the occurrence of some new need which continues to 
make itself felt, and from a new movement which this need 
originates and sustains. 

(3) "The development of organs and their power of action 
are constantly determined by the use of these organs. 

(4) "All that has been acquired, begun, or changed in the 
structure of individuals during the course of their life is pre- 
served in reproduction and transmitted to the new individuals 
which spring from those which have experienced the changes." 

But the man whose work is most completely identified with 
organic evolution is Charles Darwin (1809-82), who after 
spending many years in travel, observation, and investigation, 
published in 1858 a paper of great scientific interest. At the 
same time, by the arrangement of friends, Wallace, then in the 
Malay Archipelago, published his paper, giving essentially the 
same conclusions. In 1859 Darwin published his great work, 
"The Origin of Species," in which natural selection was more 
fully elaborated. 

All organisms vary. These variations may be due to envi- 
ronmental changes or to excess of food, to the inherited effect of 
use or disuse of parts, or to atavism, reverting to the character- 
istics of a remote ancestor, or to reversion, a character or 
structure found in more recent ancestors. Darwin emphasizes 
the fluctuating or indefinite variations as of most use in natural 
selection. Every plant or animal must struggle for existence 
because of the vast number of other plants and animals and 
because of conditions of environment, such as cold, heat, or 
drouth. This struggle is threefold: (1) with its own species; 
(2) with other species of plants or animals which may prey 
upon it or its food, and (3) against unfavorable conditions of 
climate or weather. Those which most frequently survive do 
so because of certain individual characteristics which have made 
them able to win in this struggle for existence, or, as Spencer 
says, "the fittest survive." Now, according to Darwin, nature 
takes advantage of these favorable variations possessed by the 



HISTORY AND THEORIES OF EVOLUTION 389 

survivors, and they are transmitted by heredity to their off- 
spring, while those having less favorable adaptations do not 
survive and, hence, are eliminated. Thus did Darwin think 
that species came into existence — by a gradual improvement 
of advantageous variations until the type was best adapted 
to its surroundings. ''I am convinced," he said, "that natural 
selection has been the main though not the exclusive means of 
modification." 

One of the many objections offered against this theory is the 
perpetuation and improvement of disadvantageous modifica- 
tions, such as the beautiful colors and songs of birds and adap- 
tations for fighting which render them conspicuous. Darwin 
explained many of these cases by his theory of sexual selection. 
Among the higher animals it is a fact of common observance 
that in mating the members of either sex prefer the most at- 
tractive individuals of the opposite sex. The successful rival 
wins the mate, and, of course, it is his characteristics which are 
transmitted and improved in succeeding generations. Adap- 
tations for rivalry by battle among males are explained in the 
same way. 

Among the helpful contemporaries of Darwin several must be 
mentioned. To Herbert Spencer (1820-1903), the philosopher 
and author of "Principles of Biology," we owe the phrase, 
"the survival of the fittest." Haeckel summed up the recapit- 
ulation theory of Von Baer (published in 1828) — i. e., that the 
embryonic phases of higher forms resemble or pass through the 
corresponding embryonic stages of lower forms — in his funda- 
mental law of biogenesis, that ontogeny recapitulates philogeny. 
Huxley was the author of "Man's Place in Nature." 

Dr. August Weismann (born in 1834) is the foremost oppo- 
nent of Lamarck as to transmission of acquired characters. He 
led to the critical examination of reported cases, and he claims 
that no case really shows the transmission of acquired char- 
acters. He recognizes the chromatin as the hereditary sub- 
stance or idioplasm, and calls the idioplasm of the germ cells 
germ plasm. This germ plasm, he says, is "never formed de 
novo, but it grows and increases ceaselessly; it is handed on from 
one generation to another like a long root creeping through the 
earth, from which at regular distances shoots grow up and be- 



390 THEORIES OF DEVELOPMENT 

come plants, the individuals of the successive generations." 
He further states "that only those characters are transmissible 
which have been controlled — i. e., produced — by determinants of 
the germ, and that consequently only those variations are 
hereditary which result from the modification of several or many 
determinants in the germ plasm, and not those which have 
arisen subsequently in consequence of some influence exerted 
upon the cells of the body. In other words, it follows from this 
theory, that somatogenic or acquired characters cannot he trans- 
mitted. 

"This, however, does not imply that external influences are 
incapable of producing hereditary variations; on the contrary, 
they always give rise to such variations when they are capable 
of modifying the determinants of the germ plasm. Climatic 
influences, for example, may well produce permanent variations 
by slowly causing gradually increasing variations to occur in 
the determinants in the course of generations. The primary 
cause of variation is always the effect of external influences. 
When deviations only affect the soma they give rise to temporary 
non-hereditary variations; but when they occur in the germ 
plasm they are transmitted to the next generation and cause 
corresponding hereditary variations in the body." 

The Mutation Theory. — De Vries is the chief exponent of the 
mutation theory, though Bateson also emphasizes its import- 
ance. This theory assumes that new species and varieties are 
produced from existing forms by sudden leaps. These may 
arise simultaneously and in groups, or separately and at more or 
less widely distributed periods. This new theory does not 
try to account for these sudden variations, but claims that 
"when they occur it is a striking fact that the characters tend 
to be transmitted." When a mutation appears, it will survive 
and leave descendants if it is adapted to its environment. Only 
a comparatively small amount of evidence has been found to 
support the zoologic side of proof for this theory. 

Orthogenesis is believed by many specialists, among whom 
may be mentioned Eimer, Whitman, Tower, and Ruthven. 
Development in a definite, predetermined direction, even if 
this development is harmful to the race, is called orthogenesis. 
"According to this theory, certain lines of development remain 



HISTORY AND THEORIES OF EVOLUTION 391 

stationary while others advance." The explanation most 
favored "ascribes the control of these modifications to the direct 
effects of physiochemical factors on organisms." Professor 
Whitman says, "Natural selection, orthogenesis, and mutation 
appear to present fundamental contradictions, but I believe 
that each stands for truth, and reconciliation is not distant." 

Mendel's law affirms that when mating takes place between 
two animals unlike in some characteristic, the offspring will 
often exhibit the characteristic of only one parent. This 
characteristic is said to be dominant, while the character which 
does not appear in the immediate descendants is said to be 
recessive. The hybrids which result from the crossing of ani- 
mals will produce a number of germ cells which bear only the 
pure character of one parent and the same number which bear 
only the pure character of the other parent. 

From this law follows the occurrence in the next and succeed- 
ing hybrid generations of a definite number of forms in definite 
numerical proportions. Thus, when gray rabbits are crossed 
with albino rabbits, all the immediate offspring are gray, while 
in the next generation produced by the breeding together of 
these gray hybrids there will occur in nearly every case three 
gray young to one albino. This is explained in the following 
way: the second generation is all gray because in the zygote, or 
fertilized germ cell, the chromosomes, or hereditary units, which 
bear the gray character are more potent in the color of the young 
than are the chromosomes bearing the albino character. This 
gray character is said to be dominant ; the recessive albino char- 
acters are not destroyed, but are carried over and give rise to 
chromosomes of their own character, so that in the breeding 
of two hybrids one albino germ cell from each of the two sexes 
unite to produce one albino descendant. If one of the hybrid 
dominants (gray) is mated with a recessive animal, half of the 
young are hybrid dominants and half recessive. One who has 
found out by experiment which are dominant and which are 
recessive characters may produce several distinct types within 
a species. If future experiments add support to this law, it will 
then be explained how races suddenly spring into existence and 
become established. 

By collecting evidence and arranging it in the form of pedi- 



392 THEORIES OF DEVELOPMENT 

grees, it has been possible to demonstrate in man the existence 
of several characters which show Mendelian inheritance. 
Though most of the evidence has relation to abnormal or dis- 
eased conditions, investigations are now being made concerning 
pedigrees of normal characters. One of the most easily ob- 
served is the natural color of the eye. "To what extent eye 
color may be valuable as a criterion of race it is at present im- 
possible to say, but if it is ever to become so, it will only be 
after a searching Mendelian analysis has disclosed the factors 
upon which the numerous varieties depend. 

"A discussion of eye color suggests reflections of another 
kind. It is difficult to believe that the markedly different states 
of pigmentation which occur in the same species are not as- 
sociated with deep-seated chemical differences influencing the 
character and bent of the individual. May not these differences 
in pigmentation be coupled with and so become in some measure 
a guide to mental and temperamental characteristics?"^ 
iPunnett's " Mendelism." 




?=s=f 







Equus Beds. 

t:quu%, Tapiriia, Elephat. 
Pliohippus Beds. 

PliuhippuB, Mastodon, Boa, etc. 



Miohippus Beds. 

Miohippus, Ihceratherium, Thhu 
Oreodon Beds. 
Edentatea, Uyoenodon, Hyracodon. 

Brontotherium Beds. 

MesohippiiS, Menodus, Etotheriun 



Diplacodou Beds. 

Epihippua, Amynodon. 
Dinoceias Beds. 

Tinoceras, Vintatlierium, LimnohyuB, 

OrohippuB, Helaletea, Cotonoceraa. 
Coryphodon Beds. 

Eohippua, Monkeys, Carnivores, Ungulates, Tillodonts, Rodents, 
Serpents. 



Lignite Series. 

Hydraaaurua, Dryptoaaurua. 



Pteianodoii Beds, 
Birds with Teeth, Hes2>eror 
Pterodactyls, Plesiosaurs. 



Dakota Group. 



Atla>nt68aurus Beds. 

Dinosaurs, Apatoaaurua, Alloaaurua, Na 
P'o • 



Connecticut River Beds. 
First Mammals (Marsupials), {DromatUerium). 
Dinosaur Foot-prints, Amphi 
Crocodiles (Belodony 



§ c8 



Coal Measures. 

First Reptiles (?). 



Sub-carboniferous. 
First known AmphibiauB (Labyrinthodontfl). 



Upper Silurian. 
Lower Silurian. 



Primordial. 



Laurentian. 



No Vertebrates known. 



Fig. 302.-Section of the earth's crust, to illustrate vertebrate life in America. 
(After Marsh.) (From Le Conte's Geology, American Book Co., Publishers.) 

393 



QUESTIONS, PROBLEMS, AND SUGGESTIONS 
For Study, Review, or Examination 

An animal is a living, organized being with living protoplasm as the 
essential foundation or "The Physical Basis of Life." An animal, whether 
an ameba or a bird, is more marvelous than any machine man ever invented. 
The animal has the powers of nutrition {i. e. is auto- or self-feeding), excre- 
tion (self -waste eliminating), self-metabolism (power to change substances 
into others of different chemical composition), irritability (response to 
stimuli), contractility (ability to move itself), sensitivity and special senses 
(by means of which it discovers itself and its environment), and self -repro- 
duction. It has self-defense and automatic (self) response or movement. 

The more you study and observe animals, the more marvelous and inter- 
esting they become until you enter into the spirit of nature study. Then 
you have a lifetime of enjoyment, pleasure, and profit ahead of you. En- 
rich your life. Get this spirit and sympathy with animal life, as John Bur- 
roughs and many other naturalists have done, and thus greatly enlarge 
your life's horizon. 

PROTOZOA 

1. The body of protozoans consists of one cell, as in Ameba, or a colony 
of cells, as in Gonium. How can one cell do all that is essential to an 
animal's existence — in nutrition, growth, reproduction, locomotion, de- 
fense, and sensitivity or irritabilitj'^? 

2. The symmetry of the animal body is: (1) asymmetric, as in the Ameba; 
(2) radial, as in the starfish; or (.3) bilateral, as in most of the animal king- 
dom. How does the symmetry of the body affect its locomotion? What 
kind of motion has an asymmetric animal, e. g., the Ameba? One of ' 
radial symmetry, as the starfish? One of bilateral symmetry, as the bird? 

3. What are the means and manner of locomotion, nutrition, reproduc- 
tion, behavior, and defense of Protozoa? 

4. The struggle for existence is threefold: (1) with their own kind; (2) 
with different kinds; (3) with their fivefold environment. Which do you 
consider the most severe, and why? 

5. Environment is fivefold: (1) organic or life; (2) atmospheric; (3) 
aqueous (water in its various forms); (4) igneous or heat; and (5) terranean 
(the solid earth) . Which one of this fivefold invironment affects protozoans 
most in their struggle for existence? 

394 



PORIFERA 395 

6. Heredity. — How would you define heredity, and what evidence do 
you see of it in the Protozoa? 

7. Which do you consider the more important factor in the Hves of ani- 
mals, heredity or environment? Which factor or force do you consider 
the stronger one in their existence? Why? 

8. Mind (p. 8). — Do you see any evidence of mind in Protozoa? 

9. Multiplication. — Give examples, from the text, of multiplication, 
asexual and by conjugation in Protozoa. 

10. Colonial Protozoa. — Gonium, for example, has "a group of sixteen 
cells, each cell a complete perfect animal capable of living independently, 
but all holding together to form a tiny, fiat colony" (Jordan). What 
is the difference between a colony and an individual, for example, 
a bee? 

11. Whether the animal body is one celled, as in Ameba, a colony of cells, 
as in Gonium, or many celled, as in the higher forms, does not the living 
protoplasm of Protozoa foreshadow the animal world, with all its com- 
plexity of body and animal behavior? (Mind, p. 8.) 

12. Show clearly that the Arneha is the limit of simplicity for an animal in 
body and behavior (Mind, p. 8), but that it has all the essential elements, 
or is potentially all that any of the higher forms are as to animal body and 
animal behavior. 

PORIFERA 

1. Body, many celled. The plan of arrangement of these many cells 
is in layers around a hollow center. Hence, sponges and the following 
branch, Coelenterata, are sometimes called "hollow animals." See Fig. 4. 

2. Symmetry of sponge body? Body layers? (p. 10). Body differen- 
tiation? (p. 10). 

3. Discuss increasing complexity of body structure of sponges over that 
of the protozoan body. 

4. Compare the threefold struggle for existence and the fivefold en- 
vironment of Porifera and Protozoa. Which branch shows the better 
preparedness for existence? Why? 

5. Behavior of Sponges (p. 8, Mind). — Do you discover any increasing 
complexity (advance) in mind in sponges over mind in protozoans? Would 
increasing body complexity necessitate more mind manifestations? 

6. Discuss variation in shape, size, color, structure, and use of 
sponges. 

7. Economic use of sponges to other animals and to man. See "Har- 
vesting Sponges," pp. 14, 15. 

8. Skeleton.— Comment on structure and advance over that of proto- 
zoans. 

9. Name some enemies of sponges. Why enemies? 



396 QUESTIONS, PROBLEMS, AND SUGGESTIONS 

10. Dominance. — Are sponges a dominant branch of animals? Where 
most abundant? (p. 15). Where least abundant? Why? 

11. Dispersal. — Name means and manner of dispersal. 

12. Barriers. — Name principal environmental barriers and state why 
barriers. 

CCELENTERATA 

1. Body Plan. — A two layered, sac-like body with hollow tentacles, 
e. g., the hydra (p. 18). 

2. Symmetry. — See 2 under Protozoa. 

Significance of this symmetry to the locomotion of the coelenterates? 

3. What are the means and manner of nutrition, reproduction, locomo- 
tion, behavior, defense, and dispersal? 

4. Name the most important of the eight factors or forces in the three- 
fold struggle for existence and the fivefold environment of this branch. 

5. What are the variations in the body plan (appendages mcluded), 
body nutrition, reproduction, dispersal, barriers, food, and economic use 
or value of the four classes of this branch? 

6. Note increasing complexity of the animals of this branch over 
sponges in body plan. 

7. Behavior or Mind (p. 8). — Manifestations of? Advance over 
sponges? 

8. Alternation of Generations. — Give a brief account of it in the classes 
of this branch. 

9. Specialization, differentiation, or division of labor in this branch. 
Comment on, as seen in Figs. 15, 16, 18, 21. 

10. What do the following terms mean, as used in this branch: colony; 
medusa, zooids? 

11. Compare the hydra (Fig. 10) and Physalia (Fig. 16); hydra and 
coral-polyp; hydra and sponge; and hydra and ameba, as to body plan, 
nutrition, multipUcation, defense, and animal behavior. (See Lab. Guide, 
pp. 12-14.) 

12. Primitive or Generalized Form. — From what generalized or primitive 
form do you consider that the four present classes of this branch originated? 

13. Phosphorescent Forms. — What classes of this branch furnish phos- 
phorescent animals? What is the function of the phosphorescence? 

14. Economic value to man (p. 32). 

15. What are the special body structures that interest you in the forms 
illustrated in Figs. 10 to 21? 

16. Increasing Complexity. — In what body structures or behavior 
(mind) manifestations have the coelenterates increased in complexity 
over the sponges? 

17. How would you summarize the coelenterates? 



WORMS 397 

WORMS 

1. Shape of body — flat, round, or rigid. 

2. Symmetry. — (See p. 34.) 

3. Body Structure. — (a) Skeleton, p. 34. 

(b) Coelom, or body cavity, pp. 34, 41, 65. 

(c) Segmentation, pp. 41, 65. 

4. Body. — Form, color, covering, and locomotion in the different 
branches of worms. 

5. Compare the flat worms and the round worms as to: form, body 
structure, feeding habits, habitats, use and harm to other animals and to 
man. 

6. Annulata. — Compare this branch (p. 65) with the Flat Worms (p. 
34) and the Round Worms (p. 41), as in 5. 

7. Variation. — What variations do you discover in shape, size, color, 
covering, feeding habits, habitats, and dispersal in the three branches of 
worms compared? 

8. Economics. — Make a list of worms considered from pp. 34-50, and 
from pp. 65-71, and state their interest to man and other animals. 

9. Animal Behavior. — Do you discover any advance in animal mind 
(p. 8) in worms over other animals so far studied? See Laboratory Guide, 
pp. 12-16, for Animal Behavior. 

10. Do you discover any increasing complexity in body structure and 
mind manifestations in worms over other forms so far studied? If so, what? 

11. Read and report on Darwin's Earthworm. 

12. In the threefold struggle for existence and the fivefold environment, 
which of the eight factors is most apparent in the existence of worms? 

13. "Worms are distinguished by shape. For amid the diversity we 
discover affinities with coelenterates, echinoderms, arthropt)ds, molluscs, 
and vertebrates" (Thompson). 

What affinities can you discover between worms and the forms Thomp- 
son names? Consider also the larval stages. 

14. Discuss manner and means of nutrition, multiplication, locomotion, 
defense, and behavior of worms. 

15. What is a worm? Why is a worm a worm? Is it because of heredity, 
environment, or both? Can it or will it be, was it ever anything else than 
a worm? 

16. Structure and Function of the Worm-body: 

(1) The Dermal System. Describe the skin, its structure, glands, and 
covering, if any. 

(2) The Muscular System. Note contractility and locomotion. 

(3) The Skeleton — the supporting apparatus or framework of the body. 
Do worms have a skeleton? If so, what is it? 






398 QUESTIONS, PROBLEMS, AND SUGGESTIONS 

,4) The Nervous System and Special Senses — the co-ordinating appa- 
ratus for the body systems and the mind, or animal behavior. 
' (5) The Digestive System^the means of absorption from food. 

(6) The Circulatory System — the means of blood nutrition of tissues. 

(7) The Respiratory System — the means of oxygen nutrition of tissues. 

(8) The Excretory System — the means of waste ehmination of body. 

(9) The Reproductive System — the race repair system. Note the 
function of each of the nine body systems enumerated in worms or other 
of the higher forms. 

17. Is the worm-body a typical, characteristic animal body? If not, 
what animal would you designate as a typical, characteristic, complete, 
perfect animal body? 

18. Are insect-bodies, fish-bodies, bird-bodies, mammal-bodies an im- 
provement over the worm-body model? If so, in what respects? 

19. Degeneration. — How does an animal body begin to degenerate? 
What organ or system first weakens and how does this affect other organs 
or systems? How does degeneration of the body affect the mind or be- 
havior? Give examples of degenerate worms. 

20. Increasing Complexity. — How does an animal body advance and be- 
come more complex? How does the animal mind or animal behavior in- 
crease in complexity? How degenerate? Why? 

ECHINODERMATA 

1. Body Plan. — Symmetry of the larval body? Of the adult body? 
Metamorphosis of the body? (p. 56). 

2. Living forms of this branch solitary or gregarious? Fixed or free? 
Marine or freshwater habitat? 

3. Skeleton and Covering. — Of what do they consist? 

4. Name means and manner of nutrition, reproduction, locomotion, 
dispersal, and defense. 

5. Water-vascular System. — Its structure and function? Is it found in 
any other branch? (p. 54). Why this specialization for this branch? 

6. Nervous System and Special Senses. — Of what do they consist in this 
branch? 

7. Animal Behavior in this branch as compared with that of other 
branches just studied? Any advance or degeneration? 

8. The echinoderms are a singularly isolated group (p. 64). How would 
you account for this? What is the effect of isolation on a group of animals 
or on a single species? What is the peculiarity of the hermit? Why so? 

9. Economics. — Name echinoderms of commercial, or scientific use or 
harm to man (p. 55). 

10. Hypothetic Case. — If you could do so, what changes would you make 



MOLLUSCA 399 

in the body structure of a starfish to change it to a sea-urchin? A sea- 
urchin to a sea-cucumber? A sea-cucumber to a crinoid or sea-Uly? 

11. Sequence of development and appearance of the classes of echinoderms? 
•See Geologic Distribution, Text, pp. 56, 60, 62, 64, and Fig. 302. 

12i Special characteristics of this branch. Of what interest are the 
echinoderms to you? 

MOLLUSCA 

1. Body of Mollusca. — Segmented or unsegmented? Bilaterally sym- 
metric or asymmetric? Covering? Defense? 

2. Variation in body plan and covering of the three classes of Mollusca? 

3. Economic or commercial interest or value to man? 

4. Oysters or Pearls. — Which is of more commercial value to man? 

5. Name some molluscs that are solitarj\ Gregarious. Why? 

6. Name Mollusca found in your vicinity? Use? Harm? 

7. Locomotion. — What are the means and manner of locomotion in the 
three classes of Mollusca? Rate? Name sluggish ones; active ones. 
Why is the locomotion so slow? Compensation for this slowness? Ex- 
ception: see Cuttlefishes, p. 84. 

8. Pearls. — Discuss the theory of their origin. Purpose to the mollusc? 
To man? 

9. Shells. — How do you account for Mollusca developing such great 
defensive armor? Advantages? Disadvantages to the branch? 

10. Affinities of molluscs and worms. See p. 88 for a hint. 

11. "The molluscs are the most highly organized of any of the inver- 
tebrates except the Arthropoda." Text, p. 87. Show the truth or falsity 
of this statement, according to your own way of thinking. 

12. "Chambered Nautilus." — Read it and show how and why O. W. 
Holmes has "immortalized" it. 

13. Structure and function of the moUuscan body. See 16 under Worms, 
and compare the two groups, system with system. 

14. Compare the mirid apparatus (nervous system and special senses) 
and the mind manifestations of molluscs and worms. See Laboratory 
Guide, pp. 12-16, Animal Behavior. 

15. Mind Type. — Sluggish or alert? (Cuttlefishes, p. 84.) 

16. Body Type. — Sluggish or alert? (Squid, p. 85.) 

17. Does the body-type make the mind-type, or vice versa? 

18. Name the one great specialization of the mollusc as to: (1) its body; 
(2) its mind manifestations. 

19. Dominance as a branch of the animal world. Is it persistent geo- 
logically? 

20. Summary of the moUuscan branch and its classes, past and present 
(geologically). 



400 QUESTIONS, PROBLEMS, AND SUGGESTIONS 

ARTHROPODA 

1. Symmetry of body? Segmentation of body and appendages? 

2. Appendages. — State number, arrangement, and use in each class 
of Arthropoda. 

3. What are the means and manner of locomotion, defense, and dis- 
persal in each class? 

4. Nutrition. — (Digestive, circulatory, respiratory, and excretory sys- 
tems and the organs of these systems.) 

5. Economics. — Name ten arthropods of interest or value (scientific, 
commercial, or economic). 

6. Compare the two sub-classes of Crustacea as to: (a) plan of body 
structure; (6) appendages; (c) habitat; (d) locomotion; and (e) value to 
man or to other animals. 

7. Compare the orders of class Arachnida in structure, habits, habitat, 
use and harm to man and other animals. 

8. Compare orders of Myriapnda on the same points. Ditto for the 
orders of Insecta. 

9. Enemies. — Make a list of enemies, animate and inanimate, that 
injure or destroj^ crustaceans, arachnids, myriapods, and insects (in the 
adult, larval, or egg stage). 

10. Name an arthropod that shows protective resemblance; warning 
colors or sounds; alluring colors or odors; parasitism; degeneration; mim- 
icry; commensalism or symbiosis. 

11. Eyes. — Name an arthropod with simple eyes; with compound eyes; 
with both simple and compound eyes; and one with no eyes. 

12. Compare the four clases of Arthropoda as to: (1) the head and its 
appendages; (2) the body and its appendages; and (3) the abdomen and 
its appendages. 

13. The Young. — How are the eggs and the young of Arthropoda pro- 
tected in the different classes? 

14. Wi7igs. — Name arthropods with no wings; with one pair; with two 
pairs. Why this difference? 

15. Stages of Metamorphosis. — What are the larvce of insects called in the 
different orders of insects? What insects furnish the pupa, cocoon, chrys- 
alis? What is the imago of insects called in the different orders? 

16. Name an order of insects that has no metamorphosis. Why? (see 
p. 12). 

17. Degeneration. — What orders of insects show examples of degeneration, 
and why? Of luminosity or phosphorescence? (p. 153). 

18. Odors. — What orders give examples of defensive odors? Of alluring 
odors? 

19. Glands. — Silk, wax, and others. Use of these glands? 



THE ELEVEN BRANCHES OF THE INVERTEBRATES 401 

20. Colors. — Give examples of alluring, warning, and terrifying colors; 
also of protective resemblance. 

21. Tools, weapons, or other means of offense or defense? 

22. Does Campodea show worm-like ancestry? If so, what is the line of 
descent of insects? 

23. From Campodea, or some other primitive form, how would you 
account for the orders of insects by descent with modification? 

24. Wheeler (in "Ants") attributes the dominance of ants to their (1) 
universal variability; (2) wide distribution; (3) numerical ascendancy; (4) 
longevity; (5) abandonment of detrimental specialization; and (6) versa- 
tility of their relations with plants and other animals. 

Compare other animals on these six points as to their dominance. What 
are your conclusions? 

25. Dominance. — Is success the criterion of superiority in animals and 
plants? If so, what are the superior classes of Arthropoda? The dominant 
or superior order of Crustacea? of Arachnida? of Myriapodaf Of insects, 
the dominant species of Arthropodaf 

26. Preparedness. — What arthropods are best prepared (and in what 
ways do you mean?) to maintain the struggle for existence? 

27. Compare the complexity of body structure and mind manifestations 
of Arthropoda with that of worms in general. See 16 under Worms for 
body systems and animal behavior. Laboratory Guide, pp. 12-14. 

THE ELEVEN BRANCHES OF THE INVERTEBRATES 

1. What have they in common in structure that makes them rank as 
invertebrates? 

2. How does the branch Chordata differ in structure from the inver- 
tebrates? See Chordata, p. 189. 

3. Give three general characteristics of each branch of the invertebrates, 
as to their body- and appendage-segmentation, body symmetry, body- 
structure as to body or germ layers (ectoderm, mesoderm, and endoderm). 

4. Symmetry. — What branches afford examples of radial symmetry? 
of bilateral symmetry? of asymmetric symmetry? of more than one kind 
of symmetry? Influence of symmetry on the locomotion of animals? 

5. Habitat. — What branches show aquatic forms? aerial forms? ar- 
boreal? terrestrial? subterranean? What branches show more than one 
habitat? Any exclusively marine forms? fresh-water forms? 

6. Food. — What branches have carnivorous forms? herbivorous ones? 
omnivorous ones? 

7. Locomotion. — Name and trace all means and modes of invertebrate 
locomotion. Do any branches have a common kind of locomotion? If so, 
what ones? 

26 



402 QUESTIONS, PROBLEMS, AND SUGGESTIONS 

8. Self-defense. — Name and trace all the means and modes of defense of 
the eggs, the young, or of the adult invertebrate. 

9. Rivalry. — Trace all adaptations for rivalry by (1) battle, (2) song; 

(3) color, or other means. 

10. Covering. — Name and trace through the different invertebrate 
branches all means of covering the body; state wjiat it is called and its uses 
to the animal and to man. 

11. Color. — Trace the purpose of color or color patterns. Find examples 
of warning colors, alluring colors, terrifying colors, of colors for protective 
resemblance. What gives color to an animal? 

12. Parasites. — Trace parasitism through the invertebrates. Causes? 
Results of parasitism on the parasite and upon the host? 

13. In the threefold struggle for existence, which fold is the most ap- 
parent for the invertebrates? Why? 

14. Of the five great environmental factors, which one is the most ap- 
parent in the existence of the invertebrates? 

15. Heredity. — In what ways do you see or infer that heredity holds the 
invertebrates? i. e., Why do they remain invertebrates? 

16. Recognition. — Find examples of recognition of its own or different 
species by color, sound, odor, or shape. 

17. Terrifying appearance, attitude, or sound. Find invertebrate ex- 
amples of each. 

18. Relations with Other Animals. — Find examples of: (1) solitary inver- 
tebrates; (2) gregarious ones; (3) social ones; (4) commensalism ; (5) sym- 
biosis. 

19. Multiplication. — Find examples of: (1) asexual invertebrates; (2) 
hermaphroditic ones; (3) dimorphic, trimorphic, and polymorphic ones; 

(4) parthenogenetic ones; (5) of branches that afford examples of both 
asexual and sexual ones. 

20. Show that its object is variation rather than reproduction, as there 
was reproduction long before sex existed. 

21. Dispersal. — Name direct, as well as indirect, means of invertebrate 
dispersal. 

22. Barrier s.-r-Show that large rivers, oceans, etc., are barriers to in- 
vertebrates. 

.23. Animal Behavior. — See "Animal Behavior," Laboratory Guide, pp. 
12-16. 

24. Irritability. — Trace irritability of the protoplasm from Ameba. 
Will it develop into the nervous system and special senses of the higher 
invertebrates? If not, where do the nervous system and special senses 
originate? 

25. Contractility. — Will protoplasmic contractihty develop into the mus- 
cular system, and locomotion? 



PISCES 403 

26. Trace, touch, taste, smell, sight, and hearing through the inver- 
tebrate branches. 

27. Trace evidences of automatic and reflex action. Purpose of these 
actions to animals? 

28. Egoistic Instincts. — (Instincts for the good of the individual.) See 
Laboratory Guide, p. 14, for a list of these instincts and give invertebrate 
examples of each one. 

29. Altruistic Instincts. — (Instincts for the good of the race.) See La- 
boratory Guide, p. 14, for list and find examples of each one among the in- 
vertebrates. 

30. Emotions. — Laboratory Guide, p. 16. Find invertebrate examples of 
each. Purpose of emotions in the existence of invertebrates? 

.31. Trace invertebrate sounds, memory, intelligence, and reason, if any. 
State the purpose of each to animals; to man. 

32. Compare the invertebrate body-structure with that of the chordate 
(vertebrate), as to similarities and differences. 

33. Have they both the nine systems named in 16, under Worms? 

34. Mind manifestations of the invertebrates and vertebrates. Do they 
agree, or do they differ in degree and kind? 

35. Is the invertebrate body-structure superior or inferior to the chordate 
one? The mind manifestations? Is the invertebrate body-mind superior 
or inferior to the chordate body-mind? 

36. Will either body-mind type ever advance to a higher type of body- 
mind? Will there ever be a higher type of body-mind or of mind-body? 
Why do you think so? Will either type now existing ever degenerate? 
Become extinct? 

PISCES 

1. Fins. — How do you account for the anterior and posterior paired 
fins of fishes being placed so close together as compared with the paired 
limbs in other chordates? Does the body locomotion of fishes have any- 
thing to do with this arrangement? 

2. Gills. — How do you account for the presence of gills instead of lungs 
in fishes? Advantages? Disadvantages? 

3. Fins and Scales. — Why have fins and scales? Is locomotion con- 
cerned in this? 

4. Self-defense. — Name all the ways and means of self-defense used and 
possessed by fishes. 

5. Locomotion. — Body motion, Umb motion, or both? Name all the 
modes of motion and locomotion of fishes. 

6. Enemies. — Name all enemies of fishes, both animate and inanimate. 
How do fishes combat or escape their enemies? 



404 QUESTIONS, PROBLEMS, AND SUGGESTIONS 

7. Sounds or Noises. — Name some fishes that make a sound or noise. 
Why are fishes, as a class, silent? 

8. Intelligence of Fishes. — High, medium, or low as compared with in- 
vertebrates? As compared with other classes of chordates? 

9. Dominance. — Why are fishes a dominant aquatic class? Whj^ more 
so than the amphibians or the reptiles? Why are fishes the most dominant 
aquatic chordate class? 

10. Geologic History. — What was the status of the fish class in past 
geologic time as an aquatic class? Was it dominant as compared with the 
reptilian class? See your Geology and compare the past of fishes and rep- 
tiles. 

11. Consult "American Food and Game Fishes." Of the 1000 true food 
and game fishes discussed, report things of interest, value, and variation 
in the ten leading families of fishes. 

AMPHIBIA 

1. How do you account for the amphibious life {i. e., living both in the 
water and on land) ? Advantage to the class? Disadvantage to the class? 

2. "No amphibians are marine." How do you account for this? Is 
it an advantage or a disadvantage to the class? 

3. How do you account for the other classes of chordates having marine 
forms? 

4. Limbs. — Name amphibians: (1) with four limbs; (2) some with two; 
and (3) others with none. Why this difference? 

5. Respiration. — In the tadpole stage? In the adult stage? Why 
this difference? 

6. Defense. — In the larval stage? In the adult stage? 

7. Enemies — of all kinds for the young? For the adult? 

8. Care of Young. — Various ways? Name of the young? 

9. Locomotion. — How performed in the larval and in the adult stage? 

10. Sounds or Noises. — How made? Whj' made? Name of the sound 
or noise? 

11. Variations in forms, size, and shape of the amphibian body? 

12. Hibernation, Estivation, Migration. — How and why done? Ex- 
amples? When? 

13. Degeneration. — What evidence do you discover of degenerate am- 
phibians? Examples? Purpose of this degeneration to the amphibian? 

14. Poison. — Name amphibians of a poisonous nature, like the toad. 
Purpose of this poisonous secretion? 

15. Naked Skin. — How do you account for the naked skin of the am- 
phibians, while the other classes of chordates have a covering such as 
scales, feathers, or hair? 



REPTILES IN GENERAL. 405 

16. Color and Color Changes in Amphibians. — Purpose? Find an ex- 
ample of: (1) warning color; (2) alluring color; (3) protective color; (4) 
terrifying attitude. Why does the toad swell up so big when you 
molest it? 

17. Animal behavior of this class. Compare with other chordate classes. 
See Laboratory Guide, pp. 12-16. 

18. Dispersal. — Compare with the geographic distribution of other 
chordate classes. Which has the best dispersal, and why? The least dis- 
persal, and why? 

19. Barriers. — Compare the barriers of Amphibia with the barriers of 
other chordate classes. What class has the most barriers? The least 
number of barriers, and why? Barriers animate and inanimate? 

20. Dominance. — The number of Amphibia now is only one-eighth that 
of fishes, one-fourth that of reptiles, and one-tenth that of birds. Were 
amphibians ever a dominant class? Why? Are they now at a disadvan- 
tage in the race of life as compared with other chordate classes? If so, why? 
Have amphibians sought safety in subordination? Will they ever do so? 
Compare all degenerate chordates. Have they sought safety in subor- 
dination? Why? 

21. Preparedness. — Which of the chordate classes has the best pre- 
paredness for dispersal? The least? Which class has the best prepared- 
ness to overcome barriers? The least? 

22. Which chordate class has the best preparedness to be a dominant 
class? Preparedness in what ways do you mean? 

REPTILES IN GENERAL 

1. Covering. — Covering by orders. Variations in the different orders? 
Why this varia^tion? 

2. Defense. — Give examples of reptilian defense by: (1) terrifying ap- 
pearance; (2) noise; (3) bluff; (4) color; (5) concealment? How are the 
young protected? The eggs? 

3. Colors. — Find an example of: (1) colors for protective resemblance; 
(2) warning colors; (3) terrifying colors; (4) mimicry. (Fig. 198.) Pur- 
pose of these colors to the reptiles? 

4. Sounds. — Name reptiles that hiss, rattle, bellow, or make other 
sounds or noises. Purpose of these sounds or noises to the reptile? 

5. Locomotion. — Name reptiles that crawl, creep, walk, run, fly, swim, 
or have other means of locomotion. 

6. Degeneration. — Read in your geology of the reptilian monsters of the 
past ages. How would you account for reptilian degeneration? Will the 
reptilian class ever regain its lost dominance? 

7. Dominance of Reptiles. — Compare with other classes of chordates. 



406 QUESTIONS, PROBLEMS, AND SUGGESTIONS 

8. Enemies. — Name all enemies of reptiles of the adult stage, of the 
young, or of the eggs. 

9. Name reptiles that migrate; that hibernate; that estivate. When? 
Where? How long? Purpose? 

10. Economics. — Value commercial Ij^ or scientifically as compared with 
other classes of chordates? 

11. Interest to you, as compared with other classes of chordates? ■ 

12. Dispersal. — Name all their means of dispersal. 

13. Barriers. — Name all the barriers to the dispersal of reptiles. 

14. Why is the reptilian disposition or character more disliked than that 
of any other class of chordates? Has their race environment or their race 
heredity made them so? 

15. Read Ditmars' "The Reptiles of the World'' and get his viewpoint, 
which is less hostile. Why do we fear reptiles? Is it hereditary? Do 
other animals fear snakes or reptiles in general? 

ORDER OPHIDIA 

16. How do you account for the limbless condition of snakes? How and 
why can a snake coil? How strike? 

17. Degeneration. — -What caused the degeneration of snakes? Will they 
become extinct? Why? Were they ever lizards, or are they just degen- 
erate lizards? 

18. Subordination. — What causes some animals to seek safety in subor- 
dination? Results? Name examples from each chordate class. 

19. Mimicry. — How do you account for mimicry in some snakes? (See 
p. 242 of the text.) Is it a sure means of defense? 

20. Account for: (1) the bright colors of some snakes; (2) the somber, 
or dull ones; (3) the rattles of rattlesnakes; (4) the "blow" of the "blow 
viper"; (5) some snakes being poisonous. Advantages? Disadvantages? 
Why are the poisonous ones becoming extinct, while the non-poisonous ones 
(e. g., the common garter snake) remain? 

21 . What is the secret of a snake charming a bird? Has fear on the part 
of the bird much to do with it? Is it paralysis of fear on the bird's parr? 

22. How and why do snakes get their prey as they do? Why do they 
swallow it whole? 

23. Enemies of Snakes. — Of the adult? Of the young? Of the eggs? 

24. Self-defense of snakes, their young, or their eggs. Name three 
means of snake defense. 

2.5. Compare a snake and a frog as aberrant forms of their classes. 
Are both degenerate or aberrant examples of their classes? Causes? 
What does the word "snake" mean? 

26. Name one special body characteristic of a snake; one mind charac- 
teristic? 



REPTILES IN GENERAL 407 

LACERTILIA OR LIZARDS 

27. Variation. — Note variation in form, size, and appearance of liza;rds 
figured in the text. 

28. The Heloderma (Fig. 200). — How account for its poisonous nature 
and its limited geographic distribution? Can you name other poisonous 
lizards? Is it a dominant reptile? Why? 

29. The Chameleon (Fig. 202). — How account for its power of changing 
colors? Purpose of this to the chameleon? 

30. The Horned Toad (Horned Lizard, Fig. 203). — How account for its 
structure, appearance, and habits? 

31. Where do you find the large lizards? (p. 248). The small ones? 
(p. 247). 

32. Hibernation, estivation, and migration of lizards. Give examples. 

33. The Monitor of the Nile (p. 248). — Why is it a friend to the Egyp- 
tians? 

34. Food. — What lizards are used by man for food? (p. 248). 

35. Comparison. — Compare hzards and salamanders on ten points of 
comparison of your own choosing. Which ones do you consider have the 
more complex body, the lizards or the salamanders? Which show more 
manifestations of mind? Less? 

36. Size. — Are Hzards large, medium, or small-sized, as reptiles? As 
chordates? 

37. Dominance. — Are lizards dominant or superior as an order of their 
class? Why? 

CHELONIA OR TURTLES 

38. The Shell. — What causes or conditions gave rise to the shell? Ad- 
vantages? Disadvantages? Will the shell lead to an advance or a degen- 
eration for the turtle's order? 

39. Degeneration. — How do you account for the present-day turtle's de- 
generation, as compared with the turtles of former geologic times? Will 
turtles become extinct? Why? How do you account for the size and 
habits of the turtles named on pp. 252, 253 of the text? 

40. Teeth. — How do you account for the absence or loss of teeth in the 
turtle order? How are they compensated for the absence of teeth? 

4L Aberrant Type. — Is the turtle the most aberrant reptile of its class? 
Compare the turtle and toad as aberrant chordates. Are snakes and 
turtles aberrant or degenerate examples of their classes? 

42. Noise. — What noise does the turtle make? When? Why? What 
bird makes a similar noise? 

43. Defense. — Note how it strikes. What other reptile strikes? What 
reptiles bite? 

44. Dominance. — Are turtles a dominant reptilian order? Why? Were 
they ever a dominant reptiUan order? 



408 QUESTIONS, PROBLEMS, AND SUGGESTIONS 

CROCODILIA 

45. How account for the powerful head, the stout limbs, and the strong, 
compressed tails of alligators and crocodiles? 

46. Why are they aquatic and nocturnal? Their prey? How and when 
secured? 

47. Why do they hibernate in temperate climates? Why migrate or 
estivate in dry, tropical regions? 

48. Compare the gavial, alligator, crocodile, and caiman in head, body, 
tail, and limbs. 

49. Commercial value of any of the Crocodilia? 

50. Why are crocodiles fast becoming extinct? 

AVES 

1. Feathers. — What is a feather? Name kinds, arrangement, colors, 
and uses to birds and to man. 

2. Are feathers analogous or homologous structures with scales of fishes 
and reptiles, and with the hair, fur, or wool of mammals? 

3. How account for feathers for birds? Do any have some scales? 
Give examples. Feathers for flight or warmth? 

4. The Flight of Birds.— Do their feathers, their peculiar respiration 
(p. 267), and their high temperature (p. 267) correlate for flight? What is 
flight? In what does it consist? 

5. Why are birds the most successful "flying machines"? Does suc- 
cess indicate superiority? If so, in what are fishes, amphibians, reptiles, 
and mammals superior? 

6. Observe Figs. 209, 210, and 212. Do you discover any reptilian 
affinities? Scientists claim birds have evolved from a reptilian-like an- 
cestry. Give your reasons for or against their claim. 

7. Colors. — Name birds with alluring colors; with colors for protective 
resemblance. Do birds ever change colors? If so, when and why? 

8. Defense. — Name all the ways and mean spossessed by birds either 
directly or indirectly for self-defense or for the defense of their young or 
their eggs. 

9. Enemies. — Make a list of all enemies, both animate and inanimate, 
that are detrimental to birds, their young, or their eggs. In spite of this 
formidable list, why are birds a dominant class of chordates? 

10. Migration. — Give facts and theories of bird migration. Do any birds 
hibernate? Remain active over winter? 

11. Economics. — Begin vrith the ostrich and report a list of 50 birds of 
domestic, scientific, or commercial value to man. 

12. Nests. — Report on all kinds of materials used for nests, where built, 
when built, why built, number of eggs in "clutch" for each kind named, 
time for incubation, care of young, and number of broods for each season. 



MAMMALIA 409 

13. What is a nest? Have amphibians, fishes, reptiles, and mammals 
anything that corresponds to a nest? If so, what is it called? How made? 
When? Why? When used? 

14. Intelligence of Birds. — Compare with other classes of chordates; as 
a class. 

15. Habitat of Birds. — Name some birds that are: (1) aerial (most of 
the time); (2) aquatic; (3) arboreal; (4) terrestrial; and (5) subterranean. 
What conditions have brought about these various habitats? 

16. Rivalry. ^Nsivae examples of rivalry: (1) by battle; (2) by song; and 
(3) by color among birds. 

17. Parasites. — Name internal and esternal parasites of wild birds; of 
domesticated ones. Name birds that are parasites. (See p. 302, The 
Cowbird.) Do you know of others? 

18. Animal Behavior. — ^See Laboratory Guide, p. 12, and report on the 
bird's behavior, points 1-9. 

19. Compare the bird and reptile -on points 1-9. Which shows the more 
animal behavior? 

20. Bird Pests. — Do birds ever become a nuisance or a pest? For ex- 
ample, the English sparrow. Give others. Do birds carry parasites or 
disease? How guard against them? 

21. Bird Pets. — What birds are used for pets? What was falconry? 

22. Domestication. — What birds are now or have been domesticated by 
man? For what use? 

25. Dispersal. — Name all means of dispersal by birds, their young, or 
their eggs. 

24. Barriers. — Name all barriers to bird dispersal. 

25. The Character, or Disposition of Birds. — Compare with other chor- 
date classes, the reptiles, for example. 

26. Which was first in time, the bird or the eggf Give your reasons care- 
fully? 

MAMMALIA 

1. Covering. — Name the kinds of covering of mammals and state 
their uses to the mammal and to man. 

2. Scales. — Name mammals that possess scales, e. g., the tail of a rat. 
Name other examples. 

3. Teeth. — Name and describe the four kinds of teeth possessed by 
mammals and state the use of each kind in the digestion or life of the 
mammal. 

4. In what orders of mammals do you find claws, nails, hoofs, horns? 
Purpose of each to the mammal? 

5. Glands of Mammals. — Sebaceous (oil), sudoriferous (sweat), lachry- 
mal (tear), scent, and mammary glands are all modified cutaneous glands. 



410 QUESTIONS, PROBLEMS, AND SUGGESTIONS 

Name examples of mammals with these glands. Uses of each to the 
mammal? Compare the glands of mammals with the glands of other chor- 
date classes. Name internal glands of mammals. 

6. Take questions 7-27 under Birds, making necessary changes in the 
questions to fit mammals. 

28. "Mammals are supposed to have originated from some early rep- 
tilian animal and branched off long before the birds were evolved" 
(American Animals, by Stone and Cram). State your idea of the make-up 
of this primitive reptilian ancestor of mammals. 

29. Give your idea of a primitive mammal from which may have evolved 
the mammalian orders of today. 

30. What, then, is the line of descent of chordates? Was it fish-like, 
amphibian-like, reptilian-like to primitive mammal, with birds as an off- 
shoot from some reptilian-like ancestor? What was the general structure 
and make-up of a primitive chordate? (See Fig. 152.) 

31. Order 1. Primitive Mammals. — Does the egg-laying habit show 
primitive condition? The "mammary pouch"? The cloaca? Hegner 
says: "In certain respects, the skeleton agrees with that of the reptiles." 
Would this show reptilian affinities? 

The Duck-bill. — Note its bill. For what use are the strong front toes? 
Use of the duck-bill's tail? Habitat of the duck-bull? Why is this order 
not a dominant one? 

32. Order il. — Show how these primitive mammals are in advance over 
Order 1 in the condition of the young. Their peculiar mode of locomotion? 
From the mode of life and the structure of this order, would it be a domi- 
nant order if placed in contact with order Carnivoraf Why are the animals 
of this order so restricted in their geographic distribuition? Why is the 
opossum so widely distributed as compared with other members of this 
order? 

33. Order V. Cetacea. — How do you account for the "blubber" of the 
whale? The baleen? The hairless skin? Vestigial limbs? Horizontal 
tail as the chief organ of locomotion? Was the whale ever a terrestrial 
animal? If so, what changed it to an aquatic one? What is a whale? Its 
commercial value as compared with the old days when whaling was a 
buisness? 

34. Order VI. Ungulata. — What are the hoofs of this order? Horns? 
Does any other order of mammals possess horns? Herbivorous or car- 
nivorous? Special means of defense? Teeth in this order? Name un- 
gulates domesticated by man. Uses? Ungulates of special curiosity? 
(p. 343). 

Why are ungulates a dominant order? Name their chief chordate enemy; 
their principal invertebrate enemies. 

35. Order VII. Rodentia. — Teeth of this order? Why no canines? 



MAMMALIA 411 

Voice? Defense? Useful rodents? Harmful ones? Why is it a domi- 
nant order of mammals? 

36. Order VIII. Carnivora or Mammals of Prey. — This order illustrates 
the adaptation of structure to habits. Note the sharp claws, canine teeth 
fitted for tearing, and the alertness of the Carnivora. Why are the Carniv- 
ora a dominant order? What ones furnish furs? Name some high-priced 
mammalian furs. Do any furnish food for man? Make a list of all 
Carnivora named in the text and state the use or harm of each to man and 
other animals. 

37. Order IX. Insectivora. — Why long-snouted? Nocturnal? Self- 
defense? Food? Where are they in winter? Note the adaptation of the 
mole to a subterranean life — pointed head, digging feet, and fine, soft fur. 

The Shrew. — Compare with the mous6 as to general appearance and 
show from the teeth that the shrew is not a rodent. What ones of this 
order hibernate? Why? Is hibernation correlated with their food? What 
ones are useful to man? Harmful? Why is this order not a dominant one? 

38. Order X. Chiroptera. The Bats.— Why' nocturnal? Why hiber- 
nate? Specialty, zigzag flight. How and why zigzag? Note, their 
extreme sensitivity makes them such expert flyers in the dark. Compare 
their wings with the wings of a bird. Food and feeding habits? Use and 
harm to man? Self-defense and sleeping habits? Why of interest as a 
"flying mammal"? 

39. Order XI. Primates. — Leave man out and how do the other animals 
of this order compare in use or harm to the Ungulata, Rodentia, and Car- 
nivora? But include man; then what? They are very much like man in 
their structural development. Whence came monkeys and man? From 
the same primitive stock, or from a different ancestry? Is there a "missing 
link"? If so, what is it? Missing between what? For a study of man, 
see Laboratory Guide, pp. 222-224. 

40. Name some mammahan pests and pets; some domesticated ones. 
4L Dominance. — Why is Mammalia a dominant class? 

42. Man. — Why is man the most successful dominant being on earth? 

43. Civilization. — (Define it.) Has man's civilization changed more than 
his heredity or his environment? Can you change the heredity of an 
animal or of man? Can you change an animal's inheritance? 

44. Are normal animals governed more by heredity or environment? 
Abnormal ones? 

45. What would you give as your final summary of the animal kingdom? 
How does it interest you? Why study it? What would this world be 
without animals? (You may suppose man exists.) How differ from his 
present state without animals? Without plants, but with animals? With 
plants, but without animals? 



412 QUESTIONS, PROBLEMS, AND SUGGESTIONS 

ANIMALS OF ECONOMIC INTEREST OR VALUE TO MAN 

See Text, pp. 4, 9, 14, 15, 16, 32, 35, 36, 37, 38, 39, 42, 43, 55, 62, 66, 70, 
72, 75, 76, 79, 80, 85, 93, 94, 99, 101, 103, 105, 109, 120, 125, 130, 131, 135, 
137, 140, 141, 142, 143, 145, 146, 147, 150, 151, 152, 154, 155, 156, 157, 158, 
159, 162, 165, 166, 167, 169, 170, 173, 175, 176, 180, 182, 185, among the 
Invertebrates. 

Among the Chordates, pp. 197, 203, 205, 210, 211, 213, 215, 216, 222, 
235, 242, 244, 252, 255, 257, 269, 270, 272, 279, 280, etc., through Birds 
and Mammals. Student complete the page references, then prepare a 
named list of 100 animals of economic or commercial interest to man. 
Do you discover that animals enter much into the Environment of our 
lives? Try a list of 100 Plants. Organic Ldfe is one of the big factors of 
our Environment. 



GLOSSARY 

Agamically. Without fertilization. 

Altricial. Hatched in a helpless condition, being wholly dependent upon 
the care of the parent. 

Analogous. Similar in function. 

Ankylose. To consolidate or grow two bones into one. 

Anthropologist. One versed in the science of the structure and function 
of the human body or the development of the human race. 

Apodal. Having no feet. 

Atrophy. The wasting away or degeneration of an organ. 

Biramous. Consisting of two branches. 

Callosities. Spots of hard and thickened skin. 

Caviare. The roes of sturgeons, salted and prepared for food. 

Commensalism. The association of two species of organisms, where one, 
at least, is benefited and the other not perceptibly injured. 

Crepuscular. Feeding in the dusk or before sunrise. 

Degeneration. The substitution of a lower for a higher form of struc- 
ture, the hereditary deterioration of type. 

Diastema. An intervening space, especially between the teeth. 

Dimorphism. "The condition of the appearance of the same species 
under two dissimilar forms." — Darwin. 

Distal. Away from the place of attachment to the body. 

Diurnal. Active or feeding by day. 

Diverticulum. A blind tube branching out of a longer one. 

Estivate. To pass the summer in a state of torpor. 

Gregarious. Many individuals of one species banding or herding together 
for mutual protection. 

Gular. Pertaining to the gula or throat. 

Hermaphroditism, The possession of both male and female reproductive 
organs by the same individual. 

Heterocercal. Having an unequally divided tail or caudal fin. 

Histolysis. Disintegration or dissolution of organic tissue. 

Homocercal. Having the caudal fin symmetric as to its lobes or halves. 

Homogeneous. Alike throughout, having parts of only one kind. 

Homoiothermal. Having a uniform temperature unaffected by environ- 
ment. 

Homologous. Similar in structure or origin. 

413 



414 GLOSSARY 

Irritability. That power or property by which an organism is able to 

respond to stimuli. 
Littoral. Pertaining to the shore. 

Lophophore. A disk which surrounds the mouth and bears the tentacles. 
Medusoids. Medusa-like structures. 
Metabolism. The process by which food is built up into living tissues, 

and living material broken up into simpler products in an prganism or 

cell. 
Milt. The spermatic fluid of fishes. 
Myrmecophilous. Living with ants, said of insects which inhabit the 

formicaries or nests of ants. 
Natural selection "implies that the individuals which are best fitted for 

the complex and, in the course of ages, changing conditions to which 

they are exposed generally survive and procreate their kind." — Darwin. 
Nocturnal. Feeding or becoming active in the night. 
Omnivorous. Eating both animal and vegetable food, feeding indis- 
criminately. 
Ontogeny. The development of an individual organism from its in- 

cipiency in the egg to the adult state. 
Operculum. A lid-shaped structure closing the aperture of a tube or 

shell. 
Ovoviparous, Viviparous. Hatching the eggs within the parent body, or 

bringing forth living young. 
Parthenogenesis. Reproduction by supposedly unfertilized eggs. 
Pendactyl. Having five digits. 
Pentameral. Arranged in fives. 
Philogeny. The study of the ancestry of organisms, or the history of 

the race. 
Placenta. The vascular membrane which connects the embryo with the 

mother and supplies it with nutriment. 
Poikilothermal. Having a body temperature varying with that of the 

environment. 
Polymorphism. The condition of having many forms. 
Precocial. Able to run about when hatched. 
Proximal. Near the place of attachment to the body. 
Pseudopodium. Any protoplasmic protrusion from a unicellular organ- 
ism. 
Recognition Mark. Coloration of special parts by which the members of 

one species may recognize their own kind, particularly beneficial in the 

recognition of parents by the young. 
Reversion. A return toward a recent ancestral type or character. 
Rheotropism. The directive influence upon growth exerted by currents 

of water or air. 



GLOSSARY 415 

Roe. The ova or spawn of fishes and amphibians, especially when still 
inclosed in the ovarian membranes. 

Rudimentary. In an early stage of development. 

Sarcode. The gelatinous material forming the bodies of sponges and other 
low animal forms. 

Somites. The segments of which an articulated body is composed. 

Stomodeum. The primitive mouth and esophagus found in actinozoans 
and in the embryos of annelids and arthropods. 

Symbiosis. The living together of two species of animals or plants, inti- 
mately and permanently, to their mutual advantage. 

Syndactylous. Having the toes united for some distance, but without a 
web. 

Trochosphere. That larval form of various worms, mollusks, and mol- 
luscoids which has a circlet of cilia. 

Vestige. A structure of the past left behind; a degenerate organ or struc- 
ture. 



INDEX 



Abomastjm, 337 

Acanthocephala, 44 

Acanthopteri, 215 

Acarina, 108 

Acephala, 73 

Achromatin, 383 

Acrania, 194 

Acrididse, 137, 138 

Actinophrys, 9 

Actinozoa, 26 

Adaptation, wings of birds, 263 

JEgialitis vocifera, 291 

Agalenidse, 106 

Aglossa, 73, 233 

Agonoderus pallipes, 151 

Alaudidee, 301 

Alces americanus, 342 

Aletia argillacea, 167 

Alligators, 253, 254 

Alluring colors of insects, 118 

Alopias vulpes, 205 

Alternation of generations, 8, 22 

Alytes obstetricans, 226 

Amblyopsidse, 214 

Amblystoma punctatum, 232 

Amoeba terricola, 1 

Ampelidae, 304 

Amphibia, 221 

Amphioxus, 190, 194 

Ampullae, 53 

Anacanthini, 214 

Andrenidse, 183 

Anguillidse, 213 

Anis, 298 

Annulata, 65 

Anolis, 247 

Anomia, 74 

Anopheles, 4, 156 
rossii, 157 

Anosia plexippus, 118, 171 

Anseres, 285 

Ant-eater, 319, 321, 324 

27 



Antelopes, 345 
Anthrenus scrophularice, 153 
Anthropoid apes, 375 
Anthropoidea, 372, 373 
Anthropopithecus erectus, 379 
Antilocapra americana, 344 
Ants, 174, 177 

agricultural, 180 

carpenter, 179 

communism of, 179 

corn-louse, 180 

intelligence of, 180 

mound-building, 179 

slave-making, 179 
Anura, 224, 228 
Aphididae, 140 
Aphides, 124 
Aphids, 143 
Apidse, 183 
Apis, 184 
Apoda, 228 
Aptera, 126 
Apteria, 259 
Arachnida, 103 
Araneida, 104 
Archceopteryx, 258, 369 
Arctomys marmotta, 352 
Ardea candidissvma, 228 

egretta, 288 
Ariolimax calif ornica, 83 
Aristotle, 386 
Armadillos, 324 
Aromochelys odoratus, 253 
Arthfopoda, 89 

classification of, 186 
Arthrostraca, 102, 103 
Artiodactyla, 332, 334 
Ascaris lumbricoides, 43 

nigrovenosa, 41 
Ascidians, 192 
Assimilation, 7 
Asterias vulgaris, 54 

417 



418 



INDEX 



Asteroidea, 54 
Atavism, 388 
Ateles, 374 
Attidse, 108 
Auk, 281 
Automatism, 7 
Aves, 258 

Babirusa, 335 
Badger, 360 

Baloenoptera sibbaldii, 328 
Balanoglossus, 190, 191 
Baltimore oriole, 302 
Barnacles, 91 
Bass, 215 
Bateson, 390 " 
Bats, 368, 371 
Bdelloida, 47 
Bears, 359 
Beavers, 353 
Bees, 174, 183 
Beetles, carpet, 173 

ground, 151 

myrmecophilous, 153 

tiger, 150 

water, 152 
Belostomidae, 142 
Beluga, 328 
Bettongia, 323 
Bivalva, 73 
Blackbirds, 302 
Blastostyles, 22 
Blastula, 385 
Blattidse, 134 
Blind fishes, 214 
Blissus leucopterus, 142 
Blow-flies, 155 
BombidEB, 184 
Bombinator, 227 
Bombus, 184 
Bombyliidse, 161 
Bos bonasus, 348 

grunniens, 348 

primogenius, 348 

sivalensis, 350 
Bot-flies, 156 
Bothriocephalus latus, 38 
Bovidffi, 345 
Brachiopoda, 48 
Bradypodidse, 324 
Bradypus, 324 
Branchellion, 70 
Branchipus, 90 
Brine shrimp, 90 



Buffalo fishes, 212 
Buffon, 387 
Bufo lentiginosus, 234 
Bufonidse, 234 
Butterflies, 162 

cabbage, 173 

distinguished from moths, 163 

gossamer-winged, 171, 173 

swallow-tailed, 172 



C^ciLiiD^, 229 
Calamistrum, 107 
Calamoichthys, 210 
Calasoma scrutator, 151 
Calcarea, 16 
Callinectes sapidus, 101 
Camelidse, 337 
Camels, 337 
Camelus bactrianus, 338 

dromedarius, 338 
Campodea staphylinus, 127 
Camponolus pennsylvanicus, 179 
Canidae, 361 
Cants lupus, 362 ■ 

occidentalis, 362 
Cankerworms, 165 
Capra (sgagrus, 345 

ibex, 345 

pyrenaica, 345 
Carabidse, 150 
Carapace, 90 
Caribou, 340 
Carinatse, 265, 281 
Carnivora, 356 

aquatiCj 365 

terrestrial, 358 
Carpocapsa pomonella, 164 
Cassididse, 83 
Cassowary, 278, 280 
Castor canadensis, 352 
Castoridse, 352 
Catarrhina, 375 
Cat, domestic, 364 

family, 358 
Catfish, 212 
Cattle, 345 
Caudata, 229 
Caviare, 210 
Cavities, hemal, 191 

neural, 191 
Cebidae, 373 
Cebus, 375 
Cecidomyiidse, 160 



INDEX 



419 



Cell, division of, 383 

polar, 385 

structure of, 385 

theory, 382 
Centipedes, 111 
Centrosome, 383, 384 
Cephalopoda, 84 
Cephalothorax, 90 
Ceratina dwpla, 183 
Ceratodus, 209 
Cercarise, 36 
Cercopithecidae, 375 
Cercopithecinse, 375 
Certhiidae, 305 
Cervidse, 339 
Cervus canadensis, 340 
Cestoda, 37 

Cetacea, 312, 314, 315, 318, 326 
Chsetognatha, 44 
Chaetopoda, 65 
Chamelion, 247 
Chamois, 346 
Chelae, 95 
Chelonia, 248 
Chemotropism, 7 
Chevrotain, 337 
Chigoe, 162 
Chilopoda, 111 
Chimoera monstrosa, 207 
Chimpanzee, 377 
Chinch-bug, 140, 142 
Chiroptera, 368 
Chlamydophorus, 325 
Cholaepus, 324 
Chondrostei, 210 
Chordata, 188 
Chromis, 212 
Chromosomes, 384 
Chrysemys marginata, 253 
Chylema, 383 

Chylomycterus geoynetricus, 204 
Cicada, 142 
Cicadidae, 142 
Cicindelidae, 150 
Cilia, 5 
Cirri, 91 
Cirripedia, 91 
Cistudo, 253 
Civets, 365 
Clitellum, 68 
Clubionidse, 106 
Clytus eridus, 175 
Cobweb-weavers, 107 
Coccidae, 140, 146 



Coccinellidae, 153 

Coccyges, 297 

Cockroaches, 134 

Codfish, 214 

Coelenterata, 17 

Coleoptera, 148 

CoUembola, 127 

Color, changes of, theories of, 361 

Colubrida, 243 

Columbae, 292 

Columba livia, 293 

Commensalism, 14, 65, 100, 102 

Communism of ants, 179 

Condylura cristola, 367 

Congo snake, 231 

Conjugation, 8 

Contractile vacuole, 2 

Contractility, 8, 13 

Coot, 289 

Copepoda, 91 

Coral, secretion of, 17 

stony, 29 
Cormorant, 285 
Corn-ear worm, 167 
Corvidaj, 301 
Cossidae, 164 
Cotton-boll worm, 167 
Cotton worm, 167 
Cowbird, 302 
Cowries, 82 
Coyote, 363 
Crabs, blue, 101 

fiddler, 102 

hermit, 100 

oyster, 102 

spider, 102 
Crane, 289 
Craniata, 195 
Crayfish, 90, 95 
Creepers, 305 
Cribellum, 107 
Crickets, 139 , 

Crinoidea, 62 
Crocodiles, 253 
Crocodilia, 253 
Crossopterygii, 210 
Crotalidae, 243 
Crows, 301 
Crustacea, 90 
Cryptobranchus, 231 

allegheniensis, 231 
japonicus, 231 
Ctenidia, 82 
Cteniza, 106 



420 



INDEX 



Ctenophora, 17 
Cuckoos, 298 
Culex, 156 

fatigans, 157 
Culicidse, 156 

Curled-thread weavers, 107 
Cuttlefishes, 84 
Cyanea, 17, 26 
Cyclops, 91 
Cyclostomata, 195 
Cycloturus, 324 
Cynipid^e, 176 
Cynocephalus, 375 
Cynomys, 352 
Cyprseidse, 82 
Cypress, 90 
Cysticercus, 38 
Cytoplasm, 383 



Dactylethra, 233 

Darwin, Charles, 388 

Erasmus, 387 
Dasypodidse, 324 
Dasypus sexcinctus, 325 
Dasyuridse, 321 
Deer, 339 

Delphinidoe elphineraptus, 328 
Dendrobates tinctorius, 227 
Dendrolagus, 322 
Dermophis, 229 
De Vries, 390 

Diapheromera femorata, 137 
Dictynidse, 107 
Didelphidae, 321 
Didelphys, 321 
Dimorphism of spiders, 106 

of trochelminthes, 47 
Dinophilea, 47 
Dinosauria, 256 
Diodon maculata, 204 
Diplopoda, 112 
Dipneumones, 106 
Dipnoi, 208, 220 
Dipodidse, 354 
Diptera, 153 
Dispersal of hydra, 20 

of starfish, 55 
Dodo, 293 
Dolomedes, 108 
Dolphins, 328 
Dormice, 353 

Dracunculus medinensis, 43 
Dragon-flies, 129 



Drassidse, 106 
Duck-bill, 320 
Dugong, 325 
Duplicidentata, 355 
Dyticidae, 152 



Eagles, 294 
Ear-shells, 82 
Earthworm, 65 
Ecaudata, 233 
Ecdysis, 227 
Echidna, 316 

aculeata, 319 
Echinodermata, 50 
Echinorhynchus, 44 
Economic importance of annulates, 
70 

of bats, 369 

of birds, 305-309 

of camels, 338 

of caribou, 341 

of cats, 365. 

of coelenterates, 32 

of crustaceans, 99 

of deer, 343 

of fishes, 217-219 

of hawks, 295 

of hogs, 335 

of horses, 334 

of insectivores, 368 

of insects, 125 

of moUusks, 87 

of nemathelminthes, 47 

of platyhelminthes, 40 

of protozoans, 9 

of reindeer, 340 

of reptiles, 257 

of rodents, 356 

of sponges, 14 

of sturgeons, 210 

of tapirs, 332 

of whales, 329 

of yak, 349 
Ectoderm, 17 
Ectopistes migratorius, 293 
Ectoplasm, 2 
Edentata, 323 
Eels, 213 
Elapida;, 243 
Electrotropism, 7 
Elephant, 330 

mammoth, 331 
Elephantiasis, 157 



INDEX 



421 



Elephantidse, 330 
Elephas africanus, 331 
Elephas indicus, 331 
Elk, 340 
Elytra, 149 
Empedocles, 386 
Emu, 280 
Encysting, 3 
Endoderm, 10, 17 
Endoplasm, 2 
Endopod, 90 
Entomostraca, 90 
Ephemerida, 127 
Epilachna borealis, 153 
Epomophorus, 371 
Equidse, 334 
Erinaceus europoeus, 366 
Eristalis, 175 
Eumemes fraternus, 181 
Eumenidse, 181 
Euplectella, 16 
Euspongia, 16 
Evolution, 386 
Exopod, 90 
Exoskeleton, 114 
Eye-color, 392 

Falconid^, 294 
Felidse, 358, 363 
Felis caffra, 364 

concolor, 364 

leo, 363 

maniculata, 364 

onca, 364 

pardus, 364 

tigris, 364 

uncia, 364 
Feniseca taquinius, 173 
Fertilization, 385 
Fiber osoyoosensis, 352 
Filiariasis, 157 
Fins, pectoral, ventral, 199 
Fish-moth, 127 
Fission, 8 
Fissipedia, 358 
Flagellum, 4 
Flat-worms, 34 
Fleas, 161 
Flesh-fly, 155 
FHes, 154-156 
Flounders, 215 
Fly-catchers, 301 
Formica difficilis, 179 

exsectoides, 179 



Formicidae, 179 

Foxes, 361 

Frigate, 285 

Fringillida;, 302 

Frogs, 236 

Funnel web weavers, 106 

Gall-plies, 175, 176 
Gall-gnats, 160 
GalHna;, 291 
Gallinago delicata, 291 
Gallus bankivus, 292 
Gammarus, 102 
Gar-pike, 211 
Gasteropoda, 81 
Gastrophilus equi, 156 
Gastrotricha, 47 
Gastrula, 386 
Gavial, 254 
Geese, 285 
Gemmules, 12 
Geomyidge, 354 
Geotropism, 7, 13 
Gephyrsea, 69 
Germ plasm, 389 
Gibbons, 376 
Giraffes, 343 
Giraffidaj, 343 
Glass-snake, 245 
Glires, 350 
Globigerina ooze, 9 
Goats, 345 
Gonionemus, 26 
Gonium, 1 
Gonotheca, 22 
Gophers, 354 
Gordius, 44 
Gorgonacea, 31 
Gorillas, 378 
Grackles, 302 
Grantia, 116 
Graptolites, 32 
Grebe, 28 
Gregarina, 4 
Guinea-worm, 43 
Gull, 282 
Gymnodonta, 216 
Gymnophiona, 225, 228 



Hcemopsis vorax, 70 
Hsemosporidia, 4 
Hair-worm, 44 
Halictus, 183 



422 



INDEX 



Haliolidse, 82 
Hawks, 294 
red-tailed, 295 
sharp-shinned, 295 
Hedgehogs, 366 
HeUcidae, 83 
Heliothis armigera, 167 
Helix, 83 
Hellbender, 231 
Helmet-shells, 83 
Hemiptera, 138, 140 
Hepatic cseca, 192 
Heredity, 388, 390 
Hermaphroditism of cirripedia, 
definition of, 19 
of holothuroidea, 62 
of hydra, 19 
of leeches, 69 
of mollusks, 73 
of porifera, 11 
Herodiones, 286 
Heron, 287 
Herpestes griseus, 365 

ichneumon, 365 
Hessian fly, 160 
Heterodera schachtii, 41 
Heterogeny, 40 
Heteroptera, 141 
Hippocampus, 204 
Hippopotamidse, 334 
Hippotragiis niger, 345 
Hirudinea, 69 
Hirugo sanguisuga, 70 
Hirundinidse, 304 
Hog, 335 
Holocephala, 207 
Holostei, 210 
Holothuroidea, 60 
Homoptera, 141 
Homo sapiens, 379 
Honey bee, 184 
Hooke, 382 
Hook-worm, 43 ■ 
Horned lizard, 247 

toad, 247 
Hornets, 182 
Horn-tails, 175 
Horse, 334 
fly, 156 
House fly, 154 
Humming birds, 300 
Hysenidse, 358, 365 
Hydra, 17 
viridis, 21 



91 



Hydractinea, 24, 25 
Hydroid, 21 
Hydro theca, 21 
Hydrozoa, 18 
Hyla versicolor, 234 
HyUdiE, 234 
Hylobates, 376 
Hylodes liniatus, 226 
Hymenoptera, 174 
Hypoderma lineata, 156 
Hypostome, 18 
Hyracidse, 329 
Hyrax, 329 

I eery a purchasi, 153 
Ichneumonidse, 176 
Ichthyophis, 229 
Ichthyopterygia, 256 
Iguana, 248 
Incubation, 268 
Infusoria, 5 
Inquilines, 176, 184 
Insecta, 112 
Insectivora, 366 
Intelligence' of ants, 180 

of birds, 273 
Iphiclides ajax, 172 
Irritability, 7, 8, 13 
Isoptera, 131 
lulus, 112 
Ixodes, 110 

Jackals, 362 

Jays, 301 

Jennings, on ectoplasm, 3 

Jumping mice, 354 

Kallima, 118 
Kangaroos, 322 
Katy-dids, 139 
Killdeer, 291 
Kingfishers, 297 
Kinosternida?, 253 

Labium, 133 
Labrum, 133 
Lacertilia, 243 
Lady-bugs, 153 
Lcetilia coccidivora, 164 
Lamarck, 387 
Lamellibranchiata, 73 
Lampyridse, 153 
Lancelet, 190 



INDEX 



423 



Land birds, 291 
Larks, 301 

Lasius brunneus, 180 
Leibnitz, 387 
Lemuridse, 372 
Lemuroidea, 372 
Leopard, 364 

hunting, 365 
Lepas, 92 
Lepidoptera, 162 
Lepidosiren, 209 
Lepisma saccharina, 127 
Lepomis cyanellus, 215 
Leporidae, 250, 255 
Leptoplana, 34 
Lepus, 355 

americanus, 356 

aquaticus, 355 

campestris, 356 

palustris, 355 

sylvaticus, 355 
Libellulidse, 129 
Life, Archaean, 382 

origin of, 382 
Limacidae, 83 
Limicolae, 290 
Limnaeus, 84 
Limpets, 82 
Limulus, 110 
Linckia linckia, 56 
Lion, 363 
Lithobius, 111 
Littorina, 83 
Liver-fluke, 36 
Llama, 339 
Lobster, 90, 99 
Locustidae, 138 
Locusts, 137 

seventeen-year, 143 
Longipennes, 282 
Loon, 281 

Lophobranchii, 212, 216 
Lophophore, 48 
Loris, 372 
Lutra, 359 
Lyccenidae, 173 
Lycostidae, 108 
Lymantriidae, 168 
Lynx, 364 



Macaques, 375 
Macheira, 102 
Mackerel, 215 



Macrochires, 300 
Macronucleus, 5 
Macropodidae, 322 
Macropus, 322, 323 
Madreporic plate, 52 
Malacostraca, 90, 92 
Malpighian tubes, 120 
Mammalia, 311 
Man, 379 
Manatee, 325 
Mantidae, 136 
Mantids, praying, 136 
Marine worms, 68 
Marmosets, 373 
Marmot, 352 
Marsupialia, 320 
Marten, 360 

Maryland yellow-throat, 305 
Mastigophora, 4 
Maturation, 384 
Maxilla, 133 
Maxillary palpus, 133 
May-flies, 127 
Medusae, 22 
Megachile acuta, 183 
Megachiroptera, 370 
Melanoplus atlantis, 138 

femur-rubriim, 137 

spretus, 137 
Meleagrina, 77 
Meles, 360 
Melipona, 184 
Mendel's law, 391 
Mephitis, 360 
Mesoderm, 386 
Mesoglea, 10, 17 
Mesothorax, 133 
Metabolism, 7 
Metamorphosis, 26 
Metathorax, 133 
Metazoa, 10 

Microchiroptera, 370, 371 
Micronucleus, 5 
Microtus, 353 
Migration, 274 
Millepora alicornis, 25 
MUlipeds, 112 
Milt, 212 
Mimicry of hymenoptera, 175 

of insects, 119 

of viceroy, 172 
Mink, 360 
Mitosis, 383 
Mniotiltidae, 304 



424 



INDEX 



Mole, 367 

Australian, 322 
Mollusca, 72 
Molluscoida, 48 
Molting of crayfish. 98 
Monarch butterfly, 172 
Mongoose, 365 
Monitors, 248 
Monkeys of America, 373 

Old World, 375 

orang-utan, 376 

Saki, 374 

spider, 374 

squirrel, 374 
Monobia quadridens, 181 
Monotremata, 319 
Moose, 342 
Morula, 385 
Mosquitoes, 156 
Moths, 162 

carpenter, 164 

coccid-eating, 164 

codling, 164 

gypsy, 169 

hawk, 170 

meal, 164 

owlet, 166 

tussock, 168 
Mud-eel, 229 

Multiplication, sexual, asexual, 11 
Muridaj, 352 
Musca domestica, 154 
Muscardinius avellanarius, 353 
Muscidse, 154 
Mus decumanus, 352 

minutus, 352 

musculus, 352 
Muskrat, 352 
MusteUda;, 359 
Mutation, 390 
Mya arenaria, 80 
Mydaus milictes, 360 
Mygale, 106 
Myogale nioscata, 367 
Myriapoda, 111 
Myrmecophaga jubata, 324 
Myrmecophagidse, 324 
Myrmicidse, 180 
Mytilus, 74 

Nasalis, 375 
Natica, 83 

Natural selection, 388 
Nauplius, 90 



Nautilus, 86 
Nebalia, 93 
Necrophorus, 150 
Necturus, 223, 231 
Nemathelminthes, 41 
Nematocysts, 19 
Nematoda, 41 
Nematus ribesii, 175 
Nemertinea, 39 
Neotony, 232 
Nephridia, 68, 201 
Nereis, 69 
Newts, 232 

Nictitating membrane, 271 
Night hawk, 300 
Noctuida}, 166 
Non-ruminants, 334 
Nototrema marswpiatum, 226 
Nucleoli, 383 
Nucleus, 2 
Nudibranchs, 83 
Nuthatches, 305 

Ocelli, 123 
Ocneria dispar, 169 
Octocoralla, 31 
Octopus, 85 

Odocoileus virginianus, 339 
Odonata, 129 
Odontoglossse, 286 
Odor of bugs, 141 
(Estridse, 156 
Oligocottus snyderi, 198 
Omasum, 337 
Ophidia, 239 
Ophiopholis, 58 
Ophiuroidea, 56 
Orb weavers, 107 
Orientation, 7 
Ornithorynchus, 320 
Orthogenesis, 390 
Orthoptera, 132 
Osculum, 10 
Ostracoda, 90 
Ostrea, 74 

edulis, 77 

virginiana, 77 
Ostrich, 278, 279 
Otaria jubata, 365 

ursina, 365 
Otolith, 203 
Otter, 359 
Ova, 384 

size of, 384 



INDEX 



425 



Ovihos moschatus, 348 
Oxwarbles, 156 
Oyster, 74 
drills, 83 

Paloemonetes vulgaris, 99 
Paludicolae, 289 
Panther, 364 
Papilionidse, 172 
Parameles, 321 
Paramoecium, 5 
Parasita, 141 
Parasitism of birds, 276 

of hymenoptera, 176 

of insects, 124 

of thyca, 56 
Paridse, 305 
Parr, 212 

Parthenogenesis, 124 
Passeres, 300 
Patagium, 258 
Patellidae, 82 
Pecten irradians, 77 

jacobceixs, 77 

maximus, 77 
Pedicellariae, 54 
Peduncle, 48 
Pelecanus californicus, 285 

erythrorhynchus, 285 

fuscus, 285 
Pelecypoda, 73 
Pelican, 285 
Penguin, 281 
Pennatulacea, 31 
Pepsis formosa, 181 
Perch, 215 
Perissodactyla, 332 
Periwinkle, 83 
Perlidse, 128 
Petrel, 284 
Petrogale, 323 
Phalangeridae, 322 
Phalangidea, 104 
Phalaropes, 291 
Phanerogiossa, 234 
Pharaoh's rat, 365 
Pharyngognathi, 212 
Phasmidse, 137 
Phasmomantis Carolina, 136 
Philohela minor, 291 
Phocidae, 366 
Pholas, 8 
Phoronida, 48 
Phototropism, 7 



Phrynosoma, 247 
Phyllium, 118 
Phyllocardia, 93 
Phyllopoda, 90 
Phylloxera, 145 
Phylostoma hastatum, 371 
Physa, 84 

Physeter niacrocephalus, 328 
Physteridae, 328 
Pici, 298 
Pieris, 173 
Pill-bug, 90, 102 
Pinnipedia, 365 
Pinnotheres, 76 
Pipa, 233 
Pipe-fish, 217 
Pisces, 196 
Pitheca, 374 
Planaria, 34 
Planorbis, 84 
Plasma, 383 
Platyhelminthes, 34 
Platypsylla castoris, 153 
Platyrrhina, 373 
Plecoptera, 128 
Plectognathi, 216 
Plover, 291 
Pluteus, 57, 60 
Pogonomyrmex, 180 
Polychetse, 68 
Polyergus refescens, 179 
Polypterus, 210 
Polyzoa, 48 
Pond-snail, 83 
Poneridae, 180 
Porcupines, 353 
Porpoises, 328 
Prairie-dog, 352 
Prawn, 99 
Primates, 372 
Proboscidea, 372 
Procamelus, 349 
Procyonidae, 358 
Prong-horn, 344 
Prostomium, 47 
Proteidae, 230 
Proteus, 225, 231 
Prothorax, 114 
Protoplasm, 1 

properties of, 8 
Protopod, 90 
Protopterus, 206, 209 
Protovertebrates, 191 
Protozoa, 1 



426 



INDEX 



Protozoa, malaria-producing, 4 

Pseudobranchus striatus, 230 

Pseudopodia, 2 

Psithyrus, 184 

Psittaci, 297 

Pterosauria, 257 

Pterylse, 259 

Pulicidfie, 161 

Pulmonata, 83 

Puma, 364 

Putorius fetidus, 360 

rixosus, 361 
Pygopodes, 281 
Pyralis farinalis, 164 



Quail, 292 



Raccoon, 358 
Radiolaria, 3 

ooze, 9 
Raiidse, 206 
Rail, 289 
Rana catesbiana, 236 

clmnata, 236 
Rangifer tarandus, 340 
Raptores, 294 
Rat fleas, 162 
Ratitae, 265, 278 
Recurvirostra americana, 291 
Reindeer, 340 
Remora, 210 
Reptilia, 236 
Resemblance, protective, of bats, 370 

of birds, 270 

of crayfishes, 99 

of flat- worms, 34 

of geometrids, 165 

of insects, 115 

of pipe-fish, 217 

of sea-cucumber, 61 

of sea-urchin, 58 

of weasel, 361 
special protective, kallima, 118 

mantids, 136 
variable protective, 118 
Rivalry of birds, 276, 292 

of seals, 366 
Rock wallabies, 323 
Rodentia, 350 
Rotifera, 46 
Round-worms, 41 
Ruminants, 336 



Saimiri, 374 
Salamander, 231 
maculosa, 227 
Salamandridse, 231 
Salmon, 213 
Salmonidse, 213 
Sand-stars, 57 
Sand-worm, 69 
San Jose scale, 148 
Sarcode, 11 

Sarcophaga sarracenioe, 155 
Sarcoptes scabei, 110 
Sargassum, 198 
Sauropterygia, 256 
Saw-flies, 175 
Scale bugs, 146 
Scales, ctenoid, 198 

cycloid, 198 

ganoid, 197 

placoid, 197 
Scallop, 77 

Scalops aquaticus machrinus, 367 
Schleiden, 382 
Schools of fishes, 212 
Schwann, 382 
Sciuropterus, 352 
Sciurus, 352 
Scolopendra, 111 
Scombridae, 215 
Scorpanoids, 204 
Scorpionida, 103 
Scorpions, 103 
Sea-anemone, 27 
Sea-cucumber, 61 
Sea-horse, 217 
Sea-mussels, 84 
Sea-squirt, 192 
Seals, 365, 366 
Segmentation, 385 
Self-defense of amphibians, 226 

of fishes, 204 

of glass-snake, 246 

of insects, 115 

of snakes, 241 

of turtles, 251 
Sesia, 175 
Setae, 67 

Sexual selection, 389 
Sheep, 345, 347 

bot-fly, 156 
Shrimp, 99 
Siluridaj, 212 
Simiidffi, 375, 376 
Siphonaptera, 161 



INDEX 



427 



Sirenia, 312, 314, 325 
SirenidsB, 229 
Siren lactertina, 229 
Siricidse, 175 
Skunks, 360 
Sloths, 324 
Slugs, 83 
Smolt, 212 
Snails, 83 
Snipes, 291 
Song of birds, 277 
Sorex palustris, 366 

personatus, 366 
Soricidse, 366 
Spermatozoon, 385 
Sphargis coriacea, 252 
Sphecina, 181 
Sphendon pundatum, 238 
Sphingidse, 170 
Sphynx moth, 170 
Spider, crab, 108 

ground, 106 

jumping, 108 

running, 108 
Sponges, 10-16 
Spongilla, 12 
Spongin, 11 
Spores, 4 
Sporocyst, 36 

Sporotrichum globuliferum, 142 
Sporozoa, 4 
Sporulation, 3 
Squamata, 239 
Squid, 84, 85 
Squirrels, 351 

flying, 352 
Starfish, 60 
Steganopodes, 284 
Stegocephala, 228 
Stegomyia, 4 

fasciata, 157 
Stickleback fish, 216 
Stilt, 291 
Stimulus, 7 

Stomodeum, beginning of, 26 
Stone flies, 128 
Stork, 287 

Struggle for existence, 388 
" Survival of the fittest," 388 
Swallow-tailed butterflies, 172 

tiger, 172 

zebra, 172 
Swallows, 304 
Swan, 285 



Swift, 247, 300 

Sword-fish, 205, 216 

Symbiosis, definition of, 4 
Hydra viridis and algos, 21 
hydractinea and crab, 25 
pinnotheres, 76 
sponges and crab, 14 

Syngamus trachealis, 43 

Syrinx, 267 

Syrphidae, 161 

Syrphus flies, 161 

Tabanid^, 156 
Taenia echinococcus, 39 

saginata, 38 

solium, 37 
Tamandua, 324 
Tamaus striatus, 352 
Tanagers, 304 
Tapeworm, 37 
Tapirs, 332 
Tapirus terrestris, 332 
Tasmanian marsupials, 321 
Teidse, 245 
Teleostei, 211 
Teleostomi, 209 
Teredo, 81 
Termites, 131 
Termitophily, 132 
Tern, 282, 283 
Terrapins, 252 

mud, 253 
Tessera, 26 
Testudinidse, 253 
Tetrapneumones, 106 
Thalessa, 176, 177 
Thallassophryne, 204 
Theridiidse, 107 
Thermorpha, 256 
Thermotropism, 7 
Thigmotropism, 7 
Thomisidse, 108 
Thrashers, 305 
Thrushes, 305 
Thysanura, 126 
Ticks, 110 
Tiger, 364 

Tinodera sinensis, 136 
Tissues, differentiation of, 386 
Tolypeutes, 325 
Tortoises, 253 
Tracker, 365 
Tragulidaj, 337 
Tree-frogs, 234 



428 



INDEX 



Trematoda, 35, 77 
Tremex columba, 175, 176 
Trichechidse, 366 
Trichinella spiralis, 41 
Trichinosis, 43 
Tridacna gigas, 80 
Tritonidse, 83 
Tritons, 232 
Trochelminthes, 46 
Trochosphere, 68 
Troglodytidae, 305 
Trogon, 298 
Tube-weavers, 106 
Tubinares, 283 
Tunicata, 192 
Turbellaria, 34 
Turdida;, 305 
Turtles, box, 253 

sea, 252 

soft-shelled, 252 

tortoise-shelled, 252 
Tylenchus tritici, 41 
Tympanic membrane of insects, 123 
Typhionectes, 229 
Typhlomolge rathbuni, 231 
Typhlosole, 66 
Tyrannidse, 301 

Uloborid^, 107 
Ungulata, 329 
Urochorda, 192 
Urodela, 229 
Urosalpinx cinerea, 83 
Ursidae, 359 

Vacuole, 3 
Vampires, 371 



Varanus, 248 

niloticus, 248 
Vertebrata, 195 
Vespa, 182 
Vespertilionidae, 371 
Viceroy, 172 
Viverridse, 365 
Vorticella, 7 
Vulpes, 361 

Walking-sticks, 137 
Wallace, 388 
Warblers, 304, 305 
Warning colors, 118 
Water birds, 281 

bugs, 142 
Waxwings, 304 
Weasel, 360, 361 
Weismann, 389 
Whales, 326, 328 
Whip-poor-will, 300 
Whitman, 390, 391 
Wild turkey, 292 
Wolf, 362 
Wombats, 322 
Wrens, 305 



XiPHOSURA, 110 



Yellow-fever mosquito, 157 
Yellow-jackets, 182 



Zygote, 385 



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best presentation of the subject in English. The work is indispensable." 

IHI©w(ilf i Pky§i©l©gy 

Physiology. By William H. Howell, M. D., Ph. D., Professor 
of Physiology, Johns Hopkins University. Octavo of 1020 pages, 
illustrated. Cloth, $4.00 net. 'New {6th) Edition. 

Dr. Howell's work on human physiology has been aptly termed a 
"storehouse of physiologic fact and scientific theory." You will at 
once be impressed with the fact that you are in touch with an expe- 
rienced teacher and investigator. 

Prof. G. H. Caldwell, University of North Dakota: " Of all tne text- 
books on physiology which I have examined, Howell's is the best.'" 



Hygiene. By D. H. Bergey, M. D., Assistant Professor of Bac- 
teriology, University of Pennsylvania. Octavo of 529 pages, illus- 
trated. Cloth, $3.00 net. New (5th) Edition. 

Dr. Bergey gives first place to ventilation, water-supply, sewage, indus- 
trial and school hygiene, etc. His long experience in teaching this sub- 
ject has made him familiar with teaching needs. 

J. N. Hurty, M. D., Indiana University: " It is one of the best books 
with which I am acquainted." 



lo Saunders' College Text-Books 



Persona/ Hygiene. Edited by Walter L. Pyle, M. D., Fellow 
of the American Academy of Medicine. i2mo of 543 pages, illus- 
trated. Cloth, Ji.so net. New (6th) Edition. 

Dr. Pyle's work sets forth the best means of preventing disease — the best 
means to perfect health. It tells you how to care for the teeth, skin, 
complexion, and hair. It takes up mouth breathing, catching cold, 
care of the vocal cords, care of the eyes, school hygiene, body posture, 
ventilation, house-cleaning, etc. There are chapters on food adulter- 
ation (by Dr. Harvey W. Wiley), domestic hygiene, and home gjTnnastics. 
Canadian Teacher : " Such a complete and authoritative treatise 
should be in the hands of every teacher.'" 

Personal Hygiene and Physical Training for Women By 
Anna M. Galbraith, M. D. i2mo of 393 pages, illustrated. 
Cloth, $2.25 net. New {2d) Edition. 

Dr. Galbraith's book meets a need long existing — a need for a simple 
manual of personal hygiene and physical training for women along sci- 
entific lines. There are chapters on hair, hands and feet, dress, devel- 
opment of the form, and the attainment of good carriage by dancing, 
walking, running, swimming, rowing, etc. 

Dr. Harry B. Boice, Trenton State Normal School: "It is intensely 
interesting and is the finest work of the kind of which I know." 



Exercise in Education and Medicine. By R. Tait McKknzib, 
M. D., Professor of Physical Kducation, University of Pennsyl- 
vania. Octavo of 58s pages, with 478 illustrations. Cloth, $4.00 
net. New (2d) Edition. 

Chapters of special value in college work are those on exercise by the 
different systems: play-grounds, physical education in school, college, 
and university. 

D. A. Sargent, M. D., Hemenway GjTnnasium: "It should be in the 
hands of every physical educator." 



Saunders* College Text-Books ii 



mirci ©IT liinijMir' 

Immediate Care of the Injured. By Albert S. Morrow, M. D., 
Adjunct Professor of Surgery, New York Polyclinic. Octavo of 

360 pages, 242 illustrations. Cloth, I2.50 net. Second Edition. 

Dr. Morrow's book tells you jusi what to do in any emergency, and it 
is illustrated in such a practical way taat the idea is caught at once. 
There is no book better adapted to iirst-aid class work. 

Health : " Here is a book that should find a place in every workshop 
and factory and should be made a text-book in our schools." 

A.inni®0£aini lllll^uiiitiraih@dl OflcfeicDJiiiairy 

American Illustrated Medical Dictionary. By W.A.Newman 
DoRLAND, M. D., Member of Committee on Nomenclature and 
Classification of Diseases, American Medical Association. Octavo 
of 1137 pages, with 323 illustrations, 119 in colors. Flexible 
leather, $4.50 net; thumb indexed, $5.00 net. New {8th) Edition. 

If you want an unabridged medical dictionary, this is the one you 
want. It is down to the minute; its definitions are concise, yet accu- 
rate and clear; it is extremely easy to consult; it defines all the newest 
terms in medicine and the allied subjects; it is profusely illustrated. 
John B. Murphy, M. D., Northwestern University: "It is unquestion- 
ably the best lexicon on medical topics in the English language, and 
with all that, it is so compact for ready reference." 

American Pocket Medical Dictionary. Edited by W. A. New- 
man DoRiAND, M. D. 693 .pages. Flexible leather, $1.25 net; 
thumb index, $1.50 net. New (gth) Edition. 

A dictionary must be full enough to give the student the information 
he seeks, clearly and simply, yet it must not confuse him with detail. 
The editor has kept this in mind in compiling this Pocket Dictionar>^ 

I. V. S. Stanislaus, M. D., Medico-Chirurgical College: "We have 
been strongly recommending this little book as being the very best." 

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